I think the 63 day average applies to all breeds. After a month, maybe more for such a small breed, a experienced person can feel the puppies as lumps just inside the hind legs. She needs a check up at the vet. You need to be learning the art of whelping. Knowing what you are doing can save the life of the puppies and maybe the mother. Start at
www.akc.org.
False pregnancies are common and can be quite convincing. You may have been lucky this time.