I know my last period was 5/25/09 & went to my first doctor appt on 7/8/09 which measured me at 5 weeks & 3 days with a Quantitative HGC test done showing me between 5-6 weeks. They gave me a due date of 03/07/10. Which is pretty accuarate with my ultrasound. I had another ultrasound done on 9/2/09 showing my at 13 weeks & 6 days with a due date of 03/04/10 which was still pretty accurate. Well at my last ultrasound on 09/29/09 they did another ulrasound measuring the baby's head, heart, body & said I was only measuring at 16 weeks & 4 days with a due date of 03/12/10. Is this normal? I know the exact date I conceived which would give a due date the 1st week of March.