hey terran and protoss: wall off and rush to colossi and thors quicker please, I'm not losing fast enough.   Any other zerg players feeling lost and hopeless like me?

Do not despair Zerg bretheren 
Whenever i feel lost or overwhelmed, i remember the national anthem of the zerg military! 
 
  

on a slightly less hysterical note, I would like some advice from better zerg players (all zerg players?) on what I should do about this seemingly failsafe trend in protoss and terran play.  Most players I face are rushing to these units as quickly as possible to augment their mass marines or stalkers, so I either have to assume my opponent is doing this and plan accordingly, or wait for the scout to confirm my fears, which means my asshole will soon be turned inside-out.  If they know that I know they're rushing to these units, it's not too tremendously difficult for them to counter my counter even quicker.  I'm in gold but I think it's a mistake.  please help :(

Mass Roach destroys Gateway units and Collosi. If there's no Marauders/Medivac they destroy Thors too. You probably need to work on your macro.

Scout more and macro more. If he's rushing to Collosi, amass more Roaches. As Day [9] says, when the opponent gets his first Collosi, he is not invincible. He is vulnerable, because of his lack of gateway units. You need to pre-emptively strike at that moment or before then. The longer the game drags on and you don't do anything about it, the more disadvantaged you might be.

I could give alot better advice if you posted some replays. All I've got to go on now if that you lose to Thors and Colossi.

If terran or protoss just walls off and turtles, zerg can just take half the expansions on the map.  No amounts of thors or collosi off one base will matter if you can easily replenish a 200/200 army.

Yeah sorry that video didn't really help with anything, was actually stalling while i looked for a link to a build i saw that focused on massing roaches pretty quickly that dealt with most forms of marauder rushes, or could easily be used to harrass a turtling terran / toss base while you claim the rest of the map for your own!  
 
http://www.rockpapershotgun.com/2010/11/02/genetic-algorithms-find-build-order-from-hell/comment-page-2/#comments  
 
Not sure if that will still be a valid tactic now (havent played sc2 in like, a month) but if its still a valid tactic i'd suggest giving it a try! 

Players that wall off and rush to higher tech units are often very vulnerable to early harassment. Depending on the map Mutalisks or Speedling/Baneling attacks can be great.  However it is not every that easy just me saying that isn't going to turn your games into victories.  You need to practice these builds.  As they say practice makes perfect!
 
Barring that, take advantage of the fact they are not moving out and expand.  Take one or maybe sometimes two extra bases and macro up hard.   If your economy is up massively, a 100 food roach army is going to crush the 2 Thors or Colossi the other player has.   Roaches in general are the units you want to have to hold down the ground forces, while a few corruptors will LEVEL colossi/most air units  and provide an easy transition into Broodlords.   Honestly Colossi are not that big a threat unless you have mass hydras or speedlings.  The real fear is the stalkers killing all your roaches and taking out your air units which are doing the damage to the colossi.
 
I know it sounds silly, but to play Zerg you really need to work on macro mechanics.  Always being on top of injections and spreading creep via tumors, make sure you are always using your larva.   AND SCOUT LIKE MAD!   You will have to sacrifice an overlord to it, but the information can be invaluable.  Seeing if they are going for banshees vs Thors is super important.
 
In the end practice is the only medicine.  You will lose tons of games getting the macro and scouting stuff down, but it is all a learning experience and once you have absorbed the knowledge of the timings and perfected your injection and expansion  timings you will crush nerds like only the Zerg can.  Keep fighting!

I gave up a while ago, I really want to get into it but the game is so damn disheartening.

Since thors and collosi take a pretty long time to tech up to. why not just baneling bust with mass ling or few roaches?

Requisite plug: Infestor Hydra
 
Seriously though, I pretty much agree with StarvingGamer's points, though I'd recommend getting quite a few more infestors if possible (I prefer 8 - 10), as people tend to focus them down ASAP and you can do some very fun things with all that extra energy. Also, since you're geting the infestation pit and expanding a lot, you're in a good position to get turtle-breakers like Ultralisks and Brood Lords.
 
Edit: And remember, even if they can turtle and build a maxed army that kills yours, remember: You're zerg, and you've got a bunch of expansions. Keep injecting larva and you can rebuild your entire army in the time it takes them to get one Colossus/Thor. Dorwning people in blood is a legitimate strategy.

I'm by no means a great player but yeah turtle = expand everywhere. When they do move out you can drown them in a sea of blood.  Or if you wanna apply early pressure, baneling bust. Even if you don't take them out, they'll most likely devote more of their one bases resources to defending. Muta harass is always fun too. 
But yeah, expand like crazy and deny any of his. Long games where you starve his ass out are just as satisfying as short ones.

for ZvP, when they start incorporating colossi, just start adding corruptors to your army. Don't use too many, because they limit the ground forces you can field, but a handful of corruptors absolutely decimate colossi.  Make sure to use the corruptor's ability on the colossi to drop them even faster.   
 
Grab more based and starve them out, and for the love of god don't engage the toss in a narrow choke, or they can funnel your forces with fields and colossi all day.  Hydraroach with corruptors is a pretty solid composition if they go stalker/zealot/colossi.   
 
ZvT I don't really ever see Thors anymore, I just don't find them that dangerous except on Lost Temple.  mutaling still works well here, just make sure to magic box your mutas so the splash doesn't hit all of them.  Thors aren't that dangerous to mutas if they aren't clumped up.  Most terrans I see that go heavy into thors are a pretty mech-based army, which makes them really vulnerable to air (thors often being their only antiair).  Blords help make short work of them as well, especially against siege tanks that tend to accompany most mech armies.

I'm thankful for all of the advice but a lot of it seems to be catering to perfect situations.  Like every Zerg player, I know and love the magic box technique, but it's virtually useless if the Thors are accompanied by SCVs and a handful of Marines which are auto-followed and attack moved.  As far as Colossi, letting them pick off my colonies from ranged gets me a few extra seconds, but as soon as I make any push with my army on the colossus, here come the blink stalkers, attack-moving their way to victory and maybe blinking back if they overcommit.   
 
What I'm trying to say is that Terran and Protoss can make a push that is incredibly difficult to handle with very little micro, while I am forced to react perfectly to their aggression or face total destruction.  If my attention happens to have been elsewhere while the attack begins, by the time I've hit spacebar, a quarter of my army is likely already fried.  

You're being too harsh of the other races, they aren't as easy to manage or impenetrable as you make them out to be.

Thors backed up by SCVs can be a real pain, although a sizeable force of roaches should out dps them. I wish Blizzard would change the unit attacking to kill repairing units, as it makes things like PFs really hard to kill. 
 
 
But as for terran mech, Ultras + Roaches + Zerglings is the way to go. Toss in a few mutalisks to snipe some tanks. Ultras have pretty terrible AI, but their ability to soak up damage is amazing. Roaches are incredible for the cost now, and become even better if youre getting upgrades, and zerglings are just there to use up the remaining minerals, and surround the enemy as mech is incredibly slow. 
 
Make sure youre getting upgrades though, thats the best advice I can give you as a zerg player. They really pay off. For example a tank in siege mode does 35 damage with a blast radius. Zerglings have 35hp. With 1 armor, no zerglings would die from 1 tank hit. Thats a big payoff.

I moved from zerg to protos a couple of weeks ago because i wasn't getting much luck. But given my brief time as protoss i can easily say the most annoying thing to combat against zerg is constant muta harras. 

 Don't underestimate the power of 1 or 2 Spine Crawlers.  In most situations, even if they could steamroll your front door with their force in 2 seconds, players will hang back and try to take out your static defense using their Colossi only which buys you even more time.

" I gave up a while ago, I really want to get into it but the game is so damn disheartening. "