I'm guessing you're around 25k HP and 27k armor in Frost?
I'd say get more Stam, then focus on avoidance...you should try to get to around 19% Dodge and 16% parry...totally attainable in pre-naxx gear. Enchant your boots with 22 stam and get the purple bracers from heroic OK, put 40 stam on those, by then you should have enough badges for the Valor Medal of the First War, that'll give you 1% dodge. Etc.
You're looking pretty good, need tanking trinkets, get rid of that piece of Saronite, and you should be in good shape.