The World of Warcraft Armory

I came here a few weeks ago and got quite a bit of advice, I've followed that and learned a good bit. But I feel like I could do so much more. As it stands I'm at 65% Physical mitigation from armor, which is only slightly higher than our paladin MT, yet he is technically hittable, meaning that any attack that isn't a dodge, miss, or parry, is blocked. Meanwhile I've got a measly 61% avoidance with Blade Barrier. Is this as good as things will get until I get lucky and better gear drops? Or is there something I could do to better my spec?

I'm hit capped with talents for melee, and I'm at 25 expertise with an elixir of expertise and the expertise food. 31.2k unbuffed HP as well.

Am I doomed to be our underdog tank? Or am I not counting on my cooldowns enough? I've no problem while tanking but I feel like if I'm not behind Bone Shield/IBF/Lichbourne I'm screwed. Or is it a third option and I'm paranoid?... >_>;

Overview of Tanking Stats:
Self Buffed 51%/61% Combined Mitigation (W/O BB / W/BB)
65% Physical Mitigation from Armor
31.2k Unbuffed HP
548 Defence
Hit Capped for Melee
Just under the Expertise cap. (25/26)