That sounds exactly like me.

I do wear a B in VS's push-ups, but that's only because it's Victoria's Secret and they're a bit silly.

I don't buy any of the "adds 2 cup sizes!" bras precisely because I don't want there to be a huge difference. The ones I choose just fill everything out a bit. I have the same "caved-in or lumpy" issue with normal bras, it's awful. When that happens, it seems not to mean that my boobs aren't BIG enough, but that the bra wants them to be placed differently on my body...? xD