I've completed the main story, all loyalty missions, about 6 or 7 anomaly detected missions, and a few of the side missions. I have a few side missions left, but I'm still only at level 26. Is there enough left for me to get the level 30 achievement? or do I need to play on a higher difficulty to get more exp?

I dont believe you get more xp for higher difficulty level - so don't bother with that.  I do know that you can get fairly close.  But honestly instead of worrying about it just use the same character for a second playthrough and you will hit 30 early in the second game.

ah ok, I have the long service medal, so I'll just to that, thanks!

I imported a level 60 ME1 character, did every single mission I could find, and hit 30 level right before the last boss fight.  So it is possible, but definitely difficult.

You level up after every mission, so just start a New Game + and you'll get there soon enough.

I had an imported level 60 character and made it to 30 right before the final boss battle.

" I had an imported level 60 character and made it to 30 right before the final boss battle. "

Gotta have the Long service exp bonus to ding 30 in one playthrough. Else, you'll fall between 3 and 4 levels short, depending on whether or not you have the DLC.

It's possible, but I only hit it after doing just about everything, and I had imported a level 60 and started at level 5. You may not be able to do it.

I imported a level 60 character and reached level 30.

Having imported a level fifty character, I started out at level three.  I was sure to finish every quest in the game (including one not mentioned in this here guide), and I ended up at level twenty-eight.  Obviously, if I had started at level five, I could've reached the maximum level, but barring substantial updates via future DLC, it ain't happenin'.

Nope, You wont :(  but hopefully the DLC can get people to lvl 30.