Hello! So, I had a problem like this once, my breasts were hurting pretty bad, and everyone in my grade was talking about puberty, now, I never talked to my mom about puberty, I thought it was embarrassing, or she'd get mad at me for asking "grown-up stuff" (She always does that) But when I did (like a month later, and told her about my puberty issues) she did talk to me about it, and was actually glad that I asked.
So, first of all, ask her, because you'll regret it..and, do it when no one is around or ask her if you can talk in private. Also, about bras, it matters how old you are if you are young like 10 (like me) then I suggest you wear a shelf bra. (I'm wearing one right now, under my shirt) If you are a bit older, maybe you should get a real one. If your already wearing one, I think your bra is too tight.
So..get a bra and talk to your mom. My breats are devoleping and hurting too, even though I'm just 10. And, if your breasts are hurting, it means you are going to an average girl's puberty, it happens to all girls, I also suggest you should start getting pads cuz ur period might come up soon. Anyways, hope this helped, bye!
