I remember my breasts being lumpy at that age and the cartalige moving around inside but these changes were due to my breasts growing. So many times they do feel the same way but you do need to have a doctor check and make sure you do or don't have cancer.
This would be a good time to talk to your mom as a young adult about your body and the changes. You two will become friends and can share things. Let the doctor make the decision and you not stress.
Please do write us back and let us know what happens.
The other S.