What's wrong with my body? Breasts won't stop growing and they hurt?

I'm 27, and my breasts still haven't stopped growing. I'm not a late bloomer - they started when I was 8. I had a reduction at 24, going from a K to a D, and I'm already back to an H. The worst part is that they hurt terribly. My breast size is not effected by weight change - that's actually the last place I lose from! I am on Nexplanon to control PCOS, I am unsure if that has anything to do with this. I'm miserable and contemplating a second reduction, but know that that won't stop them.