Out of the normal practice in Sri Lanka, perhaps, but from the posts here others here in the US have had them done that early.
Get the mom to a vet to be checked out, as her milk is a more likely cause than the docking since they all died.
And, I also would suggest that you get your girl spayed as soon as your vet says it is OK. As you've already learned, breeding is not something to take lightly -- not every dog that is capable of producing should be bred.