Hi, I am 19 years old. And in the past three months Iv noticed my left breast has gotten bigger and heavier. Iv been to the doc for a exam & they told me to not worry about it. It s grew up an entire cup size in the last three months. I have no signs of breast cancer either. I do have sharp pains in that lung occasionally, my doc also stated that my breast would not swell. I am worried because iv always noticed a slight difference, but nothing abnormal until now. I should be done with puberty I can t self diagnose myself anymore because Iv seen nothing but things as in breast cancer. Which I don t think is the issue. Any opinions?