
Don't panic. Newborn puppies don't always put on much weight, if at all during the first days. And fact is right now, they actually don't need lashings of milk - if you bring it on too fast, she may well run into mastitis. All the nourishment she needed to provide for her litter should have been given during her pregnancy. It's really only into the second and third week that the maximum demands will be made on her by her puppies.
Lactation is stimulated by the act of suckling so it's great that they are all nursing from her. Make sure any small puppies get latched onto the middle teats, ahead of the big bruisers!!
10, depending on the breed, is a big litter, so you may well be looking at supplementing them - half on and half off. If these puppies were really in trouble, regardless of the weight gain or loss, they'd be noisy. If they are content and she's doing her job - allowing them to nurse, cleaning them afterwards etc - my bet is all is well. If not, they'd be noisy.
Keep giving her several small meals, high in protein rather than loads of bulk and my bet is these puppies should be fine. Again if you are unsure about what's going on, bottle, or tub-feed half the litter one time, and the other half the next time. They should be kept nursing from her, to stimulate natural lactation.
I assume all of them have seen your vet - mum for a shot to clear out any retained birthing material, and the puppies to be checked for abnormalities you have missed. Unless you are experienced, this should always be done as soon as whelping is over.