Early ovulation affecting EDD?

Nadia
Might be a silly question but I'm sure I ovulated a week early this cycle. Based on a 28 day cycle my due date is 11/29. The doctor has given me an EDD of 11/26 but I'm sure I conceived on 3/1 which makes due date 11/22? 
My cycle seemed like it was 21 days and started on 2/22. 
What do you think?
I am going for a dating scan and I can go from 6 weeks so which date should I use?