Off Birth Control. Getting Irregular Periods. Started Taking Birth Control Pills, Missed Periods, Pregnancy Test Negative

I have been on birth control since I was in 8th grade. This past summer I was off of it for three months and began having an irregular period again so I got back on the pill . I missed 2 pills about three months ago and started my period right then. The next day I took the 2 pills I missed as well as the one for that day. I stopped my period that same day. For the next three periods they were on time with the birth control as to when I was to have cycle. Except I wasn t bleeding blood it came out brown and only lasted 3, 4 days tops. I have been experiencing a lot of body image negativity but have stayed roughly the same weight. I have taken a pregnancy test that came back negative but am still not convinced.