Today I am 10 weeks 1 day pregnant. I had sex with a friend one night wich was September 16. My last period was September 15, than September 22nd & so on I had sex with my current boyfriend I found out I was 10 weeks 1 day by a vaginal ultra sound. When I count back 10 weeks 1 day I'm getting the date of when I slept with my friend. He didn't because we stopped having sex.. but what worries me is precum Anyway my due date is June 22nd. When I called my Doctor the nurse told me I conceived around sep 29th what I'm curious about, is how am I coming up with Sept 16th which is 10 weeks 1 day ago? Please help.