According to my LMP I should be 31wks, but I've had 3 scans, two in first trimester and one at 20 wks, and they all dated baby back one week. So I'm 30 wks.
My only concern is baby ending up being bigger cuz my daughter was born early at 36 wks (induced due to my high blood pressure) and she was 7lbs 11oz. So if this baby is behind but not actually (I'm still skeptical) then im afraid its gonna be huge. I have to trust my Dr tho, she says since I had 3 scans that its accurate that baby is behind. Baby is healthy so far, no concerns at all. They are going to check lots on baby's size in case it is big, so I have some relief there.
I'm sure your baby is fine, and they may do another scan later to check growth.