Family history

I don't really know what I'm looking for here. I just feel like I need to talk. I'm 31 years old. My mom died when I was 21 at 53 years old from metastatic breast cancer. She was first diagnosed at 39/40 and had a lumpectomy and chemo and was in remission then at 51 she was diagnosed with stage 4 breast cancer. She was adopted so we never new her family history but I've found her birth parents and found out her birth mother died at 55 from metastasized breast/ovarian cancer. I've gotten yearly mammograms since 26 and this year I started MRI every year as well. So every 6 month I'm getting either a mammogram or MRI. I also had genetic testing and everything was negative. My fathers side of the family has about 30 people who have or had cancer. From colon to bladder to pancreatic to lung. So about a month and a half ago I noticed the left side of my upper breast was different. It feels like a lump but bigger. I had a mammogram and ultrasound and the radiologist feels the lump but can't see anything except heterogeneous bands of fibroglandular tissue. She said if it gets bigger or harder I need to be scanned again ASAP. My oncologist is sending me to see a surgeon because I'm terrified of sitting and waiting. I just want a prophylactic mastectomy so I don't have to get testing all the time and sit here worried all the time. My mom found out the 2nd time when it was too late. She was also negative for genes and so is my half sister that is her daughter.