Armpit lump

I posted over the summer in regards to a painful lump under my armpit that would come and go with my menstrual cycle. I have had this occur for about 8 years, though it got progressively worse with time. Over the summer I had an ultrasound and mammogram completed which indicated that it was likely just dense breast tissue. The radiologist had been quite concerned after the ultrasound alone however once the mammogram was completed, everyone was at ease. I also had blood work completed that came back fine.

I am posting again because for the past three months, the lump has consistently been present and painful. It hasn’t come and gone with my menstrual cycle, though I do think the swelling is a bit worse around my menstrual cycle. My doctor has offered to refer to a surgeon to have it removed due to it bothering me. I am just struggling to believe this is nothing other than accessory breast tissue as it changes so much and is so painful. There is breast cancer in my family and I’m very concerned. Are there other procedures I should be asking for? What other things could this be? Is it possible for something serious to be missed on the mammogram? I keep going back to how concerned the radiologist was after the ultrasound... any advice or guidance is greatly appreciated!