Sperm can live for up to 72 hours in the right environment. So it is possible that some of the sperm survived long enough to impregnate you. However, I think it is very unlikely. At this point, it is too late to use emergency contraception so there is nothing you can do but wait and see. If there is any chance that you would carry this child to term (on the off chance that you are pregnant), you need to stop taking the pill and use a barrier method of birth control until you know for sure if you are pregnant. Birth control pills, like any other medicine, can harm the fetus and/or cause miscarriage.