I Am Freaking Out. Went For Annual Mamm A Week

I am freaking out. Went for annual mamm a week ago. (I have been getting mamms for 15 yrs or more, I am 46). A week later got called to come back in. Have NEVER been called back. Was initially told the findings were "asymmetrical density, left breast." Day after call, I went in and did multiple 3D mamms, as well as ultrasound. Was told radiologist could see suspect place on one view of mamm, but not another. Also no mass showed up in U/S. For the record my U/S was extremely long and painful (like it hurt REALLY bad), but I have a long history of breast pain and tenderness. Radiologist finally talked to me and mentioned "architectural distortion" and said he could tell there is scarring. Asked if I had ever had chest trauma. I got a copy of the report and it said "no suspect calcifications" and "no discrete cystic or solid masses." However I am now going for an MRI. I am scared out of my mind. I have lost 4 pounds this week due to nerves. I have no family history of BC but have always been told I have dense, fibrous tissue. In fact, this report described left as "heterogeneously dense" which I know means 51-75% dense. What are my odds in all this??? Given that I have had left-side pain for a billion years, in fact had an U/S in my 20s that showed nothing, what could be happening?? He said tiny tumors can cause scarring. I am literally making myself sick. Would appreciate any other insights. What are my odds of also going on to a biopsy??? Sign me, Grateful for any insight ...