The first day of my LMP was June 17, 2009. I had sexual intercourse on the June 25th, July 1st and July 8th with an ex-partner. I then missed my period on what would have been July 15th. I had intercourse July 18th.
My ultrasound on the September 15 said I was 13 weeks pregnant. I didn't have sex at all before my last period and that means I would have got pregnant on my period but I hadn't had sex till after it. Do you know when I possibly conceived?
I have consulted my chart/wheel to give you the average date of conception for a woman who has normal 28 day cycles and ovulates mid cycle (around day 14)
- If your LMP was June 17th, conception should be on or near July 1st.
- If the ultrasound said you were 13 weeks exactly on Sept 15, conception should have been on or near June 29th.
The ultrasound correlates perfectly with your LMP. It looks like the July 1st possibility is the top of your list. All these dates are too close to say for sure, so a paternity test would be necessarily to confirm.
Don't forget the counting of a pregnancy does not start on the day of conception. Day one starts on the first day of your last period. So in your case you count back to June 17th.