If I were you, I'd try a dressage whip instead of a crop. It goes behind your leg, so the horse gets more of a leg-whip connection.
Yeah, she looks *pissed.* I knew a 25yo horse that did that kind of thing.. he started biting and bloating to avoid the girth.. and now has a permanent head-throw(not the good kind) because his back hurts so bad. My old coach doesn't care and still lets a girl run the crap outta him. She may still have a bit of pain with your weight in the saddle-- that's why she doesn't react to touches?
Try to get as many IRL opinions as possible. DIFFERENT vets, chiros, massage therapists, saddle fitters.. *something* is bothering her.