You should try heroics and LFR. I came back to WoW having taken a break after Cata. I went straight from my 2nd normal dungeon into heroics as a healer and never really had an issue apart from people with terrible damage who took 5+ minutes to kill a boss. Its gotten to the point now where heroics are just facerolled, the mechanics aren't hard for any boss and most people outgear the fights slightly.
LFR is an absolute joke. I think I could soloheal some of the fights and I have 637 ilvl. Even as a tank, the mechanics and damage are so toned down that even if you do it completely wrong, you will still get through. I have done it every week since its been available, never had a wipe, only people who have even died in the raid are DPS who just stood in fire for too long (probably 30s+...).
I have found garrisons to be a fun side event but their charm is wearing off to be quite honest. There is very little depth to the actual missions or how you equip or train followers. Since a lot of it is just random chance, there is no scope for players ever being 'good' at garrison missions. Its just farmville with wow characters.