I might have a pregnant shih tzu?

Okay, so I have a one year old shih tzu and I think she might be pregnant. (the possible daddy is a havanese, friend of mine is the owner and the puppies are playmates) I talked with the vet and have an appointment set up to find out for sure, but I just have a question out of curiosity. If she is pregnant, will ALL of her nipples do the whole grow and puff thing? A friend of mine says that depending on how many puupies she is carrying. Example: 2puppies=2nipple puffs <-lol....i wouldnt know because ive never had a prego dog before, so let me know if you actually KNOW an answer....no GUESSES please