I just added those links to help some that may have questions. As for the vet, most vets do not do breed specific homework and they look at all dogs the same. They will tell you that there is no reason not to breed your dog because they are healthy and pretty to. I have also seen them come right out and say you should breed. Vets do not always give the best advice other than medical advice.
Also that article stated that the dogs should not leave their littermates until 8 to 12 weeks old. The average pup being usually 8 to 10 wks and Toy breeds being 10 to 12 wks.