I too thought that you could get pregnant at any time, but now I know better. Here’s how it works (to my understanding). Count 9-14 days from the first day your period starts and that’s when you should start ovulating. During your ovulation time which lasts from about 9-11 days, you can get pregnant. Also, sperm can live for up to 3 days inside you, so even if you have intercourse within the 3 days before your ovulation starts, you could still get pregnant. I don’t think you can get pregnant that soon after your period ends. Don’t take this as medical fact coming from me, but that’s how I’ve read that it works.