28y/o female, no previous breast issues/family history has 3cm solid mass that is "benign fribroadipose tissue" should it be removed or is it o.k.?

Likely Fibroadenoma: I agree with your doctor that you probably have a benign tumor (Fibroadenoma) which occurs in young women. Most surgeons monitor it for a year or two before the issue of removal can be sorted out. A vast majority of Fibroadenomas do not grow in size, hence do not require removal. Check the size periodically (once every month). If it grows in size then a biopsy is recommended to exclude cancer.