Without getting a dog from an honest, knowledgable, reputable owner/breeder who keeps impeccable records of dogs' pedigrees, then there is now way to tell what your dog is. It is very possible that it is a mixed breed. No one, & I mean no one, can tell what bulldog breed a dog is just by looks. I've seen lab/boxer crosses that look more "pit bull"ish that your dog. However, I'm not stating he isn't a "pit bull", just making a point.
And as for blood tests, there is nothing that can be done to even tell you if yor dog is a Boxer vs. Poodle vs. Bichon vs. Chihuahua much less differentiate b/n the "pit bull" breeds. And as far as blood lines, well, to suggest a test for that is just laughable.