Tanking heroics at level 80
to get started, character is Slayzer, on the stormrage realm, and this The World of Warcraft Armory is the link to my armory page.
My problem is that I attempted to tank Heroic Utgarde keep, and from my understanding from all the research I've done on def capping, what my HP should be, talent specs, what my armor should be. I'm pretty much spot on, save for a few talent points which I plan to rework ASAP, now to get the chase, it was impossible, I entered the room with the proto drakes in it and died on nearly every pull, except when they went down before fire breath. I also seemed to taking an insane amount of damage, which the healer and I (We're IRL friends and have been running together for ages) thought was really abnormal. So i questioned my spec, and my gear, but after much more research, I found that I was using the gear I was expected to be using, and as I said earlier my spec is pretty much identical to the most common 80 prot warrior tanking specs.
what i'm looking for is some insight into maybe why I was going down so fast, the only theory that I have is that spell damage is eating away at my health faster than a healer can heal me.
I am open to any and all criticism of my build and gear, I need to know what I'm doing wrong.