I think that any macro like you describe would add a lot of unneeded delay into your actions. I understand that you don't want to deal with the switching, but placing the buttons/keybinding them in a way that feels more natural is always going to be better than an omnibus macro where you're wasting time after GCD each time it waits to cast a new ability.

I'd also say to just DPS when you feel like you can comfortably and not give in to the pressure. I play a SCH main and I wont swap unless I know I can get off some DoTs and spread them without my tank going much below half. If I don't think I can make it I don't.

I think it might be a fair amount easier to manage on SCH actually; we have more DoT skills that tick while we're healing once placed, we have lustrate which heals for 20% regardless of stance up to three times in a row, and we have pet support.

I know it's not a solution to your exact problem, but if WHM doesn't feel right maybe another healer job will. Good luck!