Period change

Ok so I've been on the same bc for a year now. I was having a period every month on the placebos up until November when I didn't have one. I didn't have one in December or January either. On my placebos last month I had minor cramping but I had very very light spotting for a little over a day. I also had the acne and usual constipation. I went to the doctor for a bacterial infection and they also did a pregnancy test that was negative. I guess my question is, has anyone had this happen? Like my sexual activity has increased in the past 4 months and so has emotional stress.