measuring earlier

Desireé • I'm 23, DH 27. Been together for 7 years. We have a 10 year old daughter, a 2 year old daughter and a 1 year old son. ❤❤💙

so I should be like 9week. and I went to the doctor and the baby is only measuring at 6 weeks. my last period was Feb 11. I found out when I was 3 weeks pregnant i guess. could this be from late ovulation