Get a +22 def enchant on that shield immediately. That's the 540 def sorted right there.

Sort out the rest of your enchants. Buy a blue belt off the AH that has real stats on it (or run Draktharon for it...decent. Runs at around 200G on my server, but it is definitely worth the coin.

Set up macro's for the 4 x chain heal spam (2 on tank, 2 on group) or a HW or LHW 4x spam on the tank. It is manageable. Plan for your heals. Know what
the timing is like for your tank getting low. Then allow for it.

With badges, and some rep rewards you can get your tank over 30k hp without too much drama. Pay attention to your cooldowns for bosses and such and be prepared to suck
for a while. You will get there.

I was in your situation a couple of months back mate....its all good now.