I had a lot less HP then you, after hitting 80 and was forced to tank, because no other tank was 80 then
You shouldnt have problems, but a lot ppl think, 21k hp isnt enought. you block a lot damage, so that helps you a lot. I cant look at your talents, but this should do fine: Talent Calculator - World of Warcraft
Swap you R. Defense-Glyph, after you hit ~3-4% hit.
Try a few jewelcrafter-epics, they are really good. Try to get the gold via daily quests and your to gathering-professions.
After getting the Ring and Amulet, try to get Essence of Gossamer! Change all Enchants above and you should perform well in future
Sorry if my english is'nt so good, it's not my natural language.