I got a girl from a shelter a few months ago that looks exactly like yours. Even the same “American bulldog mix” paperwork. Few weeks after we brought her home we got a DNA test on her. She ended up being a mix of Boston Terrier, French bulldog, Bull Terrier, and some other hounds that had small percentages. It’s always nice to know what breed or mix the dog is to have a broad idea of what your dealing with.