Birth control and boobs?

Okay so this may be a weird question, but I was talking to my friend about it and she said she experienced the same thing..

So before starting Sprintec (end of March 2019) i was a size 34D...but after starting i somehow got down to a 34b, so they shrunk when on the pill...? This past Sunday (10 day until AF is due) i started noticing that my boobs are very sore every so often?? I panicked for a while and still kind of am but trying not to, but I’m still on the pill and this is my 6th month, and I was telling her that I’m kind of scared of being pregnant bc I’ve never had sore boobs before, and she said it could be my boobs going back to their normal size because my body could finally be adjusted to the pill? I was told it only takes 3months max for your body to adjust, which for most i guess is true, but she said her boobs didn’t go back to normal until like a year into the pill?? Has anyone else experienced this?? It’s weird bc I’m still 8 days out from my period starting and my nipples aren’t sore it’s literally my boobs, which I’ve never experienced?? Could they really just be growing back to their normal size??