I have a 7 month old female GSP that is just finishing her first heat. Her nipples are very pronouced right now. Is that a hormonal change or does that mean she is pregnant?

How can you tell if a female is pregnant.? Her weight is exactly the same as when she started heat

There nipples do get bigger when they come in heat, especially for the first time.  Was your girl around any males?  You sound like maybe you mght have an oops breeding.  The nipples are not necessarily a good indicator that your dog is pregnant.

 I dont know, I ran a few males away one might have gotten in under the radar that I dont know about.