I am no theorycrafter , but i can give you some advice .
Indeed your gear is "bordeline" for Ulduar in my point of view . Bosses in Ulduar are real trucks and therfore hit HARD .
Your problem comes from your survival and not your threat from what you said. Your avoidance stats are "ok" but your stam is low .
Try getting pug run's through naxx25 is one of the major solutions. You can also get Ulduar gear crafts ( belt + boots ) and BoE loots ( Cape )
Whereas the sword enchant for survivability would be Life Drain ( more or less 200 stam , and will help your healers alot )
Try to get the 111stam trinket from Azjol to replace the dodge trincket ( i'm french , dont know the names)
you can get 18leatherwork stam on gloves ( if threat really is no issue )
apart from that i cannot give you more advice from my pov ... sorry