Had sex while ovulating. took ec hour later. had heavy bleeding 4 days b4 expected af for only 1 day. is pregnancy possible? or plan b side effects?

Either: The effectiveness of Plan B, when taken within 24 hours of intercourse is 95%. That is very good. However, if you have intercourse after you have already ovulated, it won't help because it works by delaying ovulation. If intercourse happened an hour after ovulation, the egg is already there and you have a chance of being pregnant. Do a home pregnancy test if you miss your period.