[luckylady]

She is a small one, so do watch her and be prepared for possible problems. I have heard of many smaller ones having problem free whelps as well. An x-ray about a week before she is due will give your vet a good idea on whether or not to expect problems due to head/pelvic ratio and also a good count on the number of pups to expect. Your vet is suggesting the smaller litter may mean a c section due to the fact that fewer pups have more room to grow and therefore may have a better chance to get to large to pass through the birth canal. Breathing louder could be because she is heavy with pups; I've noticed that a little in my girls before as well. Sounds like you've got a good connection with your vet, that's important and having a mentor there to help with the whelp is good also. I give my girls whelping pudding, it is great to give your mama AFTER she has her pups. Extra calcium is a no-no during pregnancy.
Good luck to you and your girl!