I took a quick look at your spec and there isnt anything i can see that is blatantly wrong. It looks decent. Only slight problem i have is that your relatively low hp for heroics and 10 man naxx. The easiest way to gear would be to get a group of guildies that you can run with each day to get 2xt7 pieces from badge vendor gear. Also your should try to stack stam either by gems when you get the chance OR by what enchants you can get. If you get a decent healer you really shouldnt have any problems with doing a couple of the easier heroics. Your defence and mitigation is spot on so the only thing left to do is stack stam without dropping below your def cap and roughly 50% mitigation.
Thanks for the tips guys! I definitely want to get my gear enchanted for more Stamina. Our guild enchanter's currently a bit behind on enchants, and I'm having trouble finding another enchanter. I'm figuring Greater Fort on my boots and Super Health on my Chestpiece will make an impact. Perhaps some gem upgrades as well, where I can fit them.