I am 13wks and 5days pregnant according to my last period, but 11 weeks and 2 days pregnant according to my ultrasound but do I take off 2weeks from the ultrasound date???? . I was told on 1st dec I was 7wks, (9wks and 3 days according to my period) but was I on that date truley 7weeks or 5??? I didnt have a vaginal ultrasound. My last period was on the 26th september and my cycle can range from 28 days to 34 days (bizarre I know) but I would say is an average of 34days. They have given me a due date of around about the 20th july, but im completly confused by this. I thought they were using my ultrasound dates because my period differs from my ultrasound dates by 2 weeks and 3 days roughly and the ultrasound is more accurate, but they have still given me a due date of 40weeks rather than 38, even though they are counting from conception. Shudnt my due date be around about the 7th july?? If I go back 40weeks from my due date it takes me to two weeks after my period and 38 weeks takes me to afew days before my next period was due...I already had spotting a week before then so im very confused by this all. Someone please help. Its important I know roughly how many weeks I am in fetal age.