For the last month or so my left breast has been swollen and tender - I noticed it at the end of my last period. I don't feel a specific lump or anything, but it feels generally swollen in the area behind the nipple, and heavier and fuller than the right one. It's also visibly larger and fuller when I'm topless or in a bra (I wish both were like this all the time, actually!). I know breasts may be uneven but mine have always been even up until now. They do tend to swell right before my period, but it's usually both of them and then they go back to normal once my flow starts.
Is this something I should be worried about, or is it normal to have such a fluctuation in just one breast? Anyone heard of this before or experienced it? I have a gyno appointment in a few weeks but have been nervous and was hoping to get some info from you guys.
Potentially relevant info:
30 years old, no pregnancies
copper IUD for several years
no medications, history of hormonal issues/PCOS/etc.
BMI at low end of "healthy range"
Definitely not pregnant
B or C bra cup size