I had intercourse on 8/03 and then again 8/8. I took a plan b within 12 hours of the act on the 8th. I then had intercourse the 13th among other dates. I just found out I am pregnant but I am not sure when it occurred. Did the plan b fail on the 8th or did it work and since having intercourse after I became pregnant. This is my first time using plan b and I am well aware of precaution measures.