I have been on birth control for about 5 months now. I am very good about taking my pills. I have never skipped a day, and I take them around the same time each day. I chose to take them at 12 each day, and I usually take them right at 12, or sometimes a little before but never later than 1. On my second week of pills, I had sex with my boyfriend and he finished inside me. I freaked out because I don't let him do this normally, and got plan B. I know, I know, it's awful to do this on Birth Control, but I was on the antibiotic Cefprozil the week before, so I got nervous. I am now on my inactive pill week. I normally start on this day each month, but I haven't started today. Is it normal to be late? Did my Cefprozil have me at risk for possible pregnancy? I took the plan B the very next day after sex. also, I really haven't had any side effects. Should I be worried?