
Difficult one for an inexperienced breeder - often with big litters, a bitch will take a rest midway through the whelping making it seem like she's finished, when she hasn't.
Best I can offer is you do a headcount re what the scan suggested, and when you think she's finished, then get her and her litter to your vet for a check. Take a friend with you, and the puppies in a box with a heat pad (after allowing them to have a good top up first) and also take your whelping gear with you in case she decides to produce another puppy(ies) en route. Be prepared to pull over!
With one litter where I'd spent the entire night at my then vet's Practice (this was in Canada and I didn't want to be travelling too and from there) - he had to give her a shot for each delivery and as he lived over his Practice, left he to call him back down if another whelping was delayed. By morning, he gave her a quick check and said she's empty and sent me home. I was sorting myself out, leaving hubby to sit with them - panic ....'she's having another'! Which she was. That puppy was right up where he couldn't be felt, from 'outside' or inside - even by my experienced vet. And it had been quite some time since what we thought was the last puppy was whelped.