If the nipples are big and pink and her belly has grown than that's a good sign that your pit may be pregnant. Normally if she was in heat only her nipples would get big & pink. Since she has a belly to I would say that your dog is pregnant.
My pit bull has recently gained weight and her nipples are bigger. I have a male pitt but have kept them apart as much as I can. How do I know if my pit bull is pregnant or how long she's got until her puppies come?