I just armoried you (assuming you are Wrathofdark on Dreadmaul). Your gear is ok, although you should really get the Tol Barad trinket. Its tons of mastery and you can use it every minute for a crap ton of resistance (he has some fire based attacks that this will help with as well).
Also, based on your armory, you have 51.19% dodge, 16.41% parry and 12% dodge. Counting the 5% miss, you should be able to be fully unhittable (meaning without dodging, parry or at least blocking) 82% of the time (roughly). When shield block is up, it should be 100% unhittable. That means that you are likely doing a no-no such as turning your back to the boss while engaged with him.
Make sure that when you are kiting him you dont turn your back. Also keep SB on CD when you are up there and you may want to get yourself the 4 piece T11 since its an 18 second shield wall (VERY sexy).
The damage up there is pretty significant. You may even want to use mastery/armor pots instead of a flask. Anything to get your blocked attacks up. Full hits are a healers worst enemy.
Deeps for show..... tank for dough.....