I just finished taking a 10 day antibiotic of penicillin and was told that my birth control is not effective at all when taking the antibiotic. My boyfriend and I had unprotected sex on the exact day an ovulation calculator said I was ovulating. I have had some cramping and a lot of bloating since then and was wondering what the chances are I would be pregnant. I also missed 3 consecutive days of my active birth control pills but I didn t think it would matter since I was told the birth control is not effective. Usually when I miss pills like that I spot or get my period but I have nothing. Could I be pregnant?