I don't normally ask for help since I know how to play all my characters. I haven't really touched my priest at 85 though. Sitting in a few pieces of gear from random heroics.
I specced disc when Cata came out and I found that it's no where as easy as it was in WOTLK. It's not very fun either.
I am atonement specced where you heal through smite. Thought it was cool at first but I find it pretty lame now. I use shields, smite, gheal with inner focus, pom, and penance as my main heals.
So far I've found the easiest healers to be.
#1 resto druid
#2 resto shaman
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#3 holy pally
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#4 disc priest
I healed all the heroics with those other 3 classes in blue/greens with no gems/enchants and had no problem. My priest has full gems and still I go oom.