Every dog is different! Like with humans, some dogs are doting parents and others are not.
If she is nursing and not harming the pups, I wouldn't worry too much.
Need a little more information for an informed opinion, but my best guess is that the basket is to small for everyone to exist comfortably. You can force the issue with a big box with high sides so no one can get out. I used a refidgerator box when my shepherd had 6 pups.
Just don't worry, it is imprinted in bitches to look for a quiet cozy place to give birth to their puppies. Sometimes what we may consider a safe cozy place is not the chosen "den" for the mother dog.
