Breast pain 🥺 plz help

I’m 20 and have been dealing with some breast soreness (sore to the touch and when I sit up right) for a while now. I’m a size 34 C. It’s not just around my period. I am on the shot and have been for over a year so I don’t believe it’s that. One thing is I don’t wear bras often any more. Since I got into college my style has become quite lazy and since getting my nipples pierced (they are healed fine) I maybe wear a bra once every few weeks or if I’m going somewheres in clothing that would be too obvious and when I do wear one it’s mostly sports bras. I don’t feel any lumps in my breast and I’m definitely not pregnant (I’m gay). I just wanted to know what you guys think it could be before making an appointment with my gyno.