Behind in growth

Meg

So I went on 9/5 measured at 5 weeks 5 days and then again had a scan on 9/20 should have been 7 weeks 6 days but measuring 7+3. I didn’t realize it until after I left and recalculated. Baby has a strong heartbeat of 153 and everything looked good so I was just happy about that but is this okay? To be 3 days off between scans?