
Take her to the vet for a shot to clear out any retained material. And to have the pups checked for abnormalities that may not be obvious. It is possible for a bitch to reabsorb around 5 - 6 weeks, which may have happened. If your vet thinks there are more puppies inside, he'll probably x-ray and then give her a shot.
This is why I don't do scans. They only confirm, or not, a pregnancy at the time of the scan. Not that the bitch will carry what's seen, to term. Yes it helps in terms of numbers, or if the mating wasn't planned, but if you get her checked when you think she's finished, that should cover it all.