Am I discing wrong?

So, I really loved disc healing. I picked it up in Wrath (I hated holy so much), and my love for bubbling and PoHing and things increased through Cata. With one hitch...

I never specced into atonement. I never liked the whole dps-heal mechanic. My personality settled really strongly into single-target, non-smite healing. I had a solid rotation, and I think I healed pretty well (with i370-ish gear, I helped a group get heroic Morchok down to 10%. My main issue was my own survivability--I was too squishy)

Right now, with everything I've read and seen, it feels like I HAVE to atonement heal. I know they baked in something like 25% healing into the mechanic, and I'm not sure I can make that up. But I loved the style that suited me. I am slowly working Spirit Shell into my rotation (or trying to remember. it's hard because i feel like it would work well for the focused-healing style I favor, but the people who aren't being shelled need me to care about them too!)

So, Disc-playing Ladies (and lurking gents), what do I do? Do I just force myself to try this playstyle? Is my old playstyle (no atonement) viable in any way? Could I raid heal with this style?

Help! How do I disc?