Dear jeana1102, The BI-RADS scale of rating mammograms is a scale from 1-5 with 1 being negative with nothing to comment on, and 5 being highly suggestive of malignancy. A Birads 3 rating of a mammogram means "probably benign finding - very high probablility of benignity. Short-term follow-up being recommended to establish stability". The decision about what to do at this time (6 month follow up or second opinion) would be what you feel most comfortable with doing.
I don't know why no one has answered you... Your report sounds fine... but... as a breast cancer survivor who has a sister who has also had breast cancer, I would suggest having a sonogram to look again in 3 months. After all, that doesn't expose you to radiation and they can compare what they saw this time with how it looks then. If you have especially dense breasts and are high-risk, an MRI might be more accurate for you.
Or you can also consider asking for a CA 15-3 or CA 27.29 blood test to see if it is above normal range. If it is, then you can think about asking for repeat imaging. (Read online about these blood tests first.)
I hope everything turns out well for you.