im pregnant and need to know when i concieved my baby. My last period was in the begining of nov. I had sex a couple of days after with this guy. then i had sex with my boyfriend nov 23 and i on the 24 or the 30. my du date is aug 13. i told my ob that nov 7 was the first day of my last period,which i think thats not true. that is the last day of my last period. i need help in understanding how does these cycle and ovulation works. i hope this baby is my boyfriends and not my friend.i dont know how to add all this up