how do you know when your ovulating. i read several sites and i did the ovulation calendar and i had my period feb 4th and got off it the 11th well the 16th i had unprotected sex twice, my boyfriend ejaculated in my both times. all the fertility calendars say that i would have been ovulating the 18th.. so could i have gotten pregnant from that. and could someone tell me exactly when you are most fertile. all the fertility celandars said i was "HIGHLY FERTILE" on the 16th..help???