From experience I'd say you should go do the dungeon again as a healer; I ran Aurum vale on my AST and we disbanned on the first boss because I literally could not heal them. Questioning whether it was me or them I went in a second time and healed it perfectly.
From the sounds of it the BLM was primarily at fault for you losing a lot of mana and people dying in the first place by not doing their job. I'm pretty sure if you run it a second time you'll heal it perfectly.