I know doctors base your due date off our last period but I didn’t have sex the week after my period because my husband was away for a family emergency. When he got back we had sex a few times every couple of days for the next few weeks before I found out I was pregnant when I was 3 days late. Doctors said I was 5 weeks exactly but it didn’t match my calendar. Assuming I could have gotten pregnant the moment I first had sex with my husband after he got back, or any time after that, I would be less than 5 week. I had an ultrasound done today and They gave me a new due date. I know due dates don’t really matter since most babies are not born on their due dates but I’m just curious as to which method is more accurate.