My chihuahua is 7 weeks pregnant has put on 600gms in 2 weeks large belly swollen nipples and increased appetite. how come the vet can only feel a full uterus but no puppies?

Are you sure she mated, if she did she should have a big bellie, if carrrying alot and big nipples. My chihuahua is also 7 weeks pregnant and ive been told to feel for the pups myself by placing my hand on her belly. You can feel small kicks at 8 weeks pregnant you will really see them kick and move about. Ive been breeding for 3 years now and not all pregnancies are the same. Keep an eye on her and give her lots of protein like eggs, cottage cheese. If your vet cannot feel the pups maybe she has alot of them and there is no room left in her. If not then id ask the vet if shes not pregnant then why has she put on the weight and showing signs of pregnancy. Hope this helps and good luck