help girls!!

vc
So I took a Plan B, out of nervousness because he didn't cum, but I knew about pre-cum. After I took it, four days later I got my, what I think it was, period. It was heavy and I had period like cramps. I usually get my period around the 30th or 31st, but since I took the plan b, I got it on the 18th. I am now on birth control, and I am not on my sugar pills, but I am feeling like I should be on my period, since it is the 1st. Should I stop my pills, or just wait until my sugar pills so I'll have my period?