Hi i had my first scan at 12 weeks which is the dating scan here in the uk. I was absolutely positive of my due date as i have a regular cycle. I know the first day of my last period and also know the exact dates of ovulation. I was supposed to be 12 weeks and 2 days at my scan but they said i am 13 weeks and 3 days. This makes me 8 days further on than i thought? How is that possible when i know the dates of last period and ovulation dates? Soo confused!!