how far am i disadvanted for playing frost dk? (bg blitz only)

i read that frost dk seems to be pretty weak right now. im wondering how far im disadvantaged for it?

i played against a unholy right now and he just face rolled me even when i used all my cds. same to rogues. i seem to loose vs every rogue.

i play blitz only right now and my dk has only ~430k hp. most of the enemies have 450-500k hp. i cant tell how important the gear diff is when i get killed in two globals by a 500k hp enhancemenet shaman. having different gear in rated pvp just sucks.

i just play dk for 3 weeks, so i know im not playing perfectly yet. but anyways the question remains how far am i disadvanted by it or is frost dk ~averagely strong right now?