What!!!! thats crazy. It is just like a women being preganet. You can't stop your dog from stretching. If she is you will know at about six to seven weeks her nipples will start growing then her belly. Was this a planned pregnatcy? I hope not because it does not sound like you know what to do. What breed is she? That will make a big differents on what needs to be done for her to have them. Some breeds have no probablems and others need c-sarions or you to be there to cut the cords for them. Sorry about my spelling
There is a pregnancy test for dogs. You can also have the dog x-rayed at around 48 days to see how many actual pups are inside. That would be helpful on the day of delivery so you know when she is finished.