Check her ear shape and the length and shape of her snout, usually staffies have a smaller snout and not such a big smile. Also the ears are a slightly different shape and seem to stand up like 'Batfink' ears when they are alert. I took mine to the vet and they were less inclined to think she was pit-bull, either way she's got a fantastic personality and thats all that matters! Maybe if you post a picture people will let you know what they think?