Firm mass of some sort

I have an appointment with a breast Dr on Friday but to ease my mind a little I was wondering if anyone has had this happen. I’m an avid wearer of sports bras. I have really big boobs and sports bras are the comfiest. Now, I am currently 20 weeks pregnant my boobs are starting to get bigger and my sports bras is fitting a little snug. I’ve noticed my left has a mass type thing when I take my bra off just about 3 weeks ago. My OB said it could be from hormones and got referred to see a breast specialist. Now, my right one just popped up just a couple days ago in the same exact spot my right one is in. Both do go away when I take my bra off for a couple of hours. Does anyone know what this could be?