Your puppy is just so small. Its so sad that the breeder had you take her home at such an early age and she was sick to boot.
If you can;t reach your vet until Monday, maybe you should call your local small animal hospital and ask them what to do?
The place I take my dogs to is a small animal hospital as well and I know they will answer any ones questions free of change when they call.
Until then you might want to try and give her more nutri-cal as a couple others have mentioned. You normally can't give too much nutri-cal.