My 15 year old daughter has a large lump in each breast

When my daughter was around 12 she came to me complaining about a pain in one of her breasts. She said a few days later a tiny lump apeared which went away within a couple weeks (I'm assuming this was a breast bud). Then a while later, within a month or so, said the lump was back but was getting a little bigger. Since then the same thing has happened in the other breast (happened around a year later to the other one) and the lump in each breast has been there ever since (they arent growing anymore but are fairly big). She says they don't grow other than some swelling and soreness before her period. They are fairly large and take up a pretty big portion of her 'a' cup breasts. She is now 15, turning 16 soon and the lumps are still there butI'm a little hesitant to take her to the doctor because of my past experiences with them. I'm making this post because I'm pretty sure that this just has to do with hormonal changes and development but but I feel like my daughter and I both need some reassurance and/ or an answer to if this sounds normal. She has also repeatedly been conncerned that the lump in each breast is interfering with growth as she hasnt noticed much breast growth/ growth spurts in her breasts and I wasn't sure if that was possible. Any responses are greatly appreciated, Thanks