Dating Scan

Vee

Question, has anyone had a dating scan that was incorrect? I’m asking because I tracked this entire process down to the date of ovulation and according to my LMP I’m 9 weeks tomorrow. I was 7 weeks and 6 days on the date of my scan but the tech said I was 6 weeks and 5 days which doesn’t add up. This is my first time going through this so I’m just wondering. Any input is helpful thanks!!