So I went to the doctor and had a sono gram. And she told me I was 3 weeks pregnant, and what I’m trying to figure out is the conception date, does it mean I got pregnant 3 weeks before or sooner than that because of what I’ve been reading if the fetus is 3 weeks than the conception was roughly 2 weeks before. I know it sounds bad but I’m trying to figure out who the father is, I had 2 partners and 1 I only slept with once and that was exactly 3 weeks before I went to the doctor. I know I can look at my last menstral and find out but I had just gotten off depo and never had a period

One week after conception you are considered to be three weeks pregnant. So you would have conceived one week before your appointment. This is because ovulation typically takes place 2 weeks after the first day of your period, and that is the day doctor count from when determining your due date.(the first day of your last period) . So when you miss your first period, you are actually considered to be 1 month pregnant, though you just conceived two weeks prior.. Hope this helped.