Try changing your mind set, it is not an option for her to go inside it is a command she must follow. Don’t think about it, then she will stop and pull or lie down just do it. I also adopted my pit and the more they relax around you and trust you the more their personality comes out. Mine wouldn’t like most dogs go near the door to the Vet, now I just walk and she follows, I tell myself in my head with some attitude that there just isn’t any option and sure enough it works.
Also having some patience and setting her boundaries, she will love you for it, they love boundries and having a reliable routine that you follow, it makes them soooo happy.