Does FCC normally light up on MRI?

I am 37, a mom of 4 kids 10 and under, with extensive BC on my father's side and my little sister died from cancer (not breast) at 29. I started seeing a high risk Dr. at the breast care center last January after I felt what I described as a thickening in the upper exterior of both breasts but mainly the left. The did a baseline mammo then immediate u/s on the left breast and told me I had dense breasts and likely what I was feeling was just normal tissue, bi-rads 3. I was told I'd need to alternate mammo and MRI every 6 months due to being high risk from the family history and I should consider genetic testing even though my grandmother tested negative for BRCA. This summer I tried to schedule the MRI but since the mammo showed a finding it flagged my chart and I couldn't get it scheduled without a follow up mammo. In Sept I had the follow up on the left breast and I immediately scheduled the MRI for Dec (even though the Dr. said I could wait until March.) I received the same report in the mail from the mammo, probably benign, bi-rads 3 (at this point I'm guessing they can't really tell due to the dense tissue). I had the MRI and the area in the left breast enhanced (type 2, non mass) and there was a fibroadenoma on the right. The radiologist called me to tell me it was probably fine, but warranted a biopsy, bi-rads 4. They scheduled me for diagnostic and biopsy yesterday. They did a full mammo (said I was due for my yearly screening) then took me to u/s for the left breast. It is a teaching hospital so the first radiologist said they'd look for the area on u/s and if they could find it they'd do the biopsy that way if not I may have to have a MRI guided biopsy. He also stated the area had changed or grown since the Sept mammo. He went to get the attending who came in and did the u/s again then said she thought it was likely just normal hormonal changes (I assume Fibrocystic Changes) and that I should wait a cycle or two and come back for another follow up mammo then we could see about a biopsy if needed. I'm not much of a wait and see person, so I asked her to just do the biopsy. My question is would fibrocystic tissue normally enhance on MRI only on the one side? I know that MRI is very sensitive, but the mammos never show anything, so why would I monitor it that way? I think I was just annoyed she was wanting me to take her personal opinion instead of a biopsy, the only way to really know.