To Wait or not to Wait

I hope I am posting in the right location: I am 41 years old and began having regular mammograms early (three years ago) as a precaution due to hormonal treatments I have been on for the past several years for another condition (treatment includes Letrozole). About a month ago I started feeling heaviness in my breast. I was not sure what it was, but knew that it did not feel “right”. It was time for my annual mammogram and OB/GYN visit, so I quickly scheduled my annual mammogram & pap. I had the mammogram first (at the office) and then met with my OB/GYN. I told her of my heavy breast feeling and some generalized itchiness that occurs on occasion. She found/felt a lump that is about two fingers wide. . My doctor seems fairly convinced that this is a cyst. She told me it would most likely not show up on the mammogram and that if it does not, to follow up with her in three months. I received the mammogram results back yesterday and they were negative. I am feeling a little anxious and worried as I can now feel the lump myself. It is smooth (consistent w what I’ve read about cysts) & slightly painful if pushed. It seems as though there are other small lumps near it, though I cannot tell if this is just regular breast tissue. Should I wait the three months to go for my follow up, or is this something that requires more urgent attention? Part of me says that something isn’t right, however, my doctor has been wonderful and accurate with other less serious health issues that I have brought to her. Am I overthinking this? I can’t help but feel for this lump every night for changes - it has been the same for three months, if not slightly firmer.