I forgot to mention the male. He is twice the size of my girl. She is approx. 5 1/2 lbs and he is 12 lbs. That was another thing I had talked to the vet about as I thought the male should be smaller, or at least comparable in size but they said the pups grow according to the mom's size.
I think I will call the vet tomorrow and take her in just to be sure. I tried feeling her tummy (sorry, can't remember the correct term for it) to see if I could feel anything different but I don't know exactly what I should or shouldn't be feeling, so that didn't work out so well for me.
Thanks for your help!