I have the same problem. Righty is a cup size bigger I would say. DS is only 6 weeks old and favours righty so I'm hoping it doesn't get even bigger! It's noticeably bigger now though than after I had DD.
I'm really hoping they even out eventually but not holding my breath. I've always bought bras to fit the bigger one. Never gone to the extent of padding lefty but may need to depending on what happens after BF this time.
Has anyone seriously considered a boob job post-babies? I've thought about it but never that seriously. I'd be too terrified of everything that could go wrong! Then again, ask me in a couple of years!