Period missed?!?!?!

Last month, I was bleeding during ovulation and again on my periods days. Also I had sex during that month and only used the pull out method, no pills or condoms. A month later (THIS MONTH) I was bleeding during ovulation again, had sex about a week later, and now I passed through all my period days and I didn't bleed at all, it was suppose to end a day ago and I didn't get it at all, not a single cramp or any sign of it, what's up with that?!?!