So I've been on birth control pills for about 2 months now. I've been very responsible taking it at the same time daily. I was on antibiotics (amoxicillin) for a week, and now I'm on my second sugar pill and I still haven't gotten my period. I'm a bit worried because I just had unprotected sex and just heard that antibiotics can interfere with the concentration of the birth control. So my question is.. Is it okay if I take Plan b?