Your defense is too low - you need minimum 535 for heroics and 540 for raid bosses.
HP is a bit low too - 20k.
Enchant your gear (stamina or defense as needed), replace your green +str gems with +stamina gems, get some leg enchants, socket your belt for stamina, head enchant asap. You should be able to get uncrittable and add a couple thousand health that way, at which point you're probably good for some of the easier heroics and offtanking 10-man stuffs with a decent healer.
In terms of spec, shift anger management --> deep wounds, shift 3 from cruelty to AtT. Prot side, get improved Thunder clap filled out, and improved Revenge over Improved Spell reflect. Otherwise it looks good.
Sorry if I'm to the point, writing from work and don't have time for anything more in-depth. Good luck getting into heroics and raids - have fun!