There's only 2 ways to look at it when I play DRK especially if the run is pretty rough.

Either I am playing bad OR the healer is. Or if you're really unlucky the DPS make the healers life incredibly difficult.

Reading your post at the beginning said plenty. You got stuck at a boss because your healer was awful. Now to back this up properly. I have a very good friend who also happens to play Tank and Heal. An in some cases we feel like we spoil one another because we do well together.....but if she wants to play DPS. I have to think more about what I'm doing. Am I dealing with a good healer or a bad one? To be really blunt and somewhat mean here. It becomes glaringly obvious when I have a bad heal. So I'm left with 2 choices.

1) Play it slower so we get through it.
2) Or deal with the struggle an hope I rotate my cooldowns well enough to compensate for the problem.