
Most breeders I know start introducing puppy porridge or other liquidised puppy foods at 3 weeks but you could have started earlier with such a large litter just to supplement what they SHOULD be getting from their mum.
If mum is genuinely only feeding some of them at most twice a day and for only a few sucks at a time you really will have to do something a.s.a.p. I can only go by my own experience but my litter of 8 pups was still being regularly fed by mum during the day and also with her overnight at that age and I'd started supplementing their diet too.
Don't want to sound like I'm telling you off as you are obviously trying to do the right thing by seeking advice but I do think it's important that you know whether she's feeding them overnight or not. Is there some reason she can't be trusted to be penned in with them overnight? If she's happy around them then she should be at least visiting them regularly during the day to feed and clean them and then you can always let her out for a break to relieve herself, get fed, have a cuddle and play with you etc.
I don't have all the answers but personally I think these puppies should be getting a LOT more food and attention from both their mum and you.
Good luck, Teri