The vet can give your dog a shot, that will abort the puppies and bring her back into heat. So if you can keep her protected from males for another three weeks, you can avoid the pups. Your dog is too young to have pups and be healthy, but the pups would probably be ok. Unless you are showing your dog, and she becomes a champion, there is no reason NOT to spay her and avoid unwanted litters. Millions of dogs die in shelters each year, and they are usually pet store pups or backyard breeders dogs. Before you breed remember that 60% of your darling puppies will die in a shelter!