This is not normal at your age if it is not proportionate with your weight . If you gain overall weight along with breast size then acceptable . U can keep a measurement reference or weight record for better understandings.
If you also feel any lump / discharge / pain then it is concernworthy and should not be ignored .
Next Steps
I understood your concern and noted the problem as well .I need to ask few more details to make a diagnosis and start treatment and advice which suits you. Pl consult me on Practo , so that I can help you better.book a time slot as per your convenience for consultation.