Have you been booked in for a follow up appointment? I had a scan at 12 weeks and was asked the same questions as you. The fetus only measured 7wks and 3 days and there was no heartbeat. I was told there and then that it was a missed miscarriage.
If you are 100% sure on your dates then it doesn't sound too hopeful - I hope I'm wrong.
well the same thing happened to me i miscarried march 20,,i had a U/S the week befor that i was supposed to be 7 weeks and my fetus was only 4,,that was like march 13 they put me on bed rest and told me not to do any heavy lifting just to basically stay in bed all day and rest,,and march 20th i miscarried,,so yes it could be very possible