
Thing is if you feed them then Mum won't make any milk, you could also be giving them idigestion.
Before you started feeding them were they gaining any weight? Even if they were not gaining much in first three days but not loosing then it is best to encourage lactation in the bitch.
Plenty of food offered 4 times a day at least, with a high liquid intake. If it is complete food and she isn't drinking much soak the food as well.
There is no replacement for mothers milk, and if you can keep the pups ticking over and gaining reasonably then you can start early weaning as soon as they eyes are open if weight gain a bit slow. Bottle fedign should really be a lst resort, and should be applied to biggest pups so that the smaller ones get the benegit of Mums milk.