I would think you could definitely get by in some Lower ones 1-3, but you could use some gear to make your life easier. Just Farming via Assaults and upgrading to max etc. Then Enchanting your Gear and such.
My Advice is at First Worry about Healing…leave the DPS and Interrupts to the Tanks and DPS to Focus. Healer DPS isn’t going to Make or Break any keys you are likely to do.
But Some DPS can help your heals, it all depends on your talents. Bare min, I would say Flame Breath on CD. For Trash the Highest Lvl you can afford, on a Boss Rank 1. When Not Healing spam Living Flame as Dps on a target to fish for EB Procs.