When did she start doing this? Are you giving her a calcium supplement? It is unusual for a bitch to leave puppies at such a young age. If she starts to shake or stagger get her to the vets immediately, as this could be eclampsia.
I would try to reduce the amount you are helping feed the puppies, as she may be thinking that as you are willing to do it, you can take over! Take her out on a lead into the garden and then take her back to them, but make sure she can get out of the whelping box and away from them if she needs to, but confine her to the same room. Have you got a heat lamp on them, because if so she may be too hot, so make sure she can get away from the heat source, also the puppies although they need to be kept warm if they are too hot they will be sprawled out all over the next box. If they are cold they will huddle together. Best thing is if they are lying close but not huddled.
This is probably just that she is a maiden bitch, not sure what to do now she has produced these babies, and some bitches are just not maternal. Keep weighing the babies to make sure they are gaining weight. Plan to worm them at two weeks old with a liquid puppy wormer (I use Panacur 10%) and if she is still not feeding them properly herself then you can think about weaning them at between two and three weeks, by introducing a very sloppy puppy porridge. Be warned though that once weaning starts she will stop cleaning up after them. As there are eight I would plan to start to wean them at three weeks anyway.
One other thing, don't be tempted to allow all and sundry in to visit the mum and pups, she could get upset by this and decide to leave them altogether.