If they keep throwing their hands make sure your hands are soft and quiet. Maybe swap to a softer bit like a regular D ring snaffel or an eggbutt copper roller (what I use on my TB that throws his head). The roller gives them something to mess with instead of throw their head. Also check teeth and gums often!
I would first get her teeth checked, and maybe even consider a bit less bridle or hackamore.
I would try I softer bit, and maybe a tie down for awhile too! Getting teeth checked is always a good indicator too! (:
if she is throwing her head back if you pull hard make sure to get her teeth checked to see if she is in any pain or not; there isn't really a bit for that unless you maybe just try a plain snaffle and go back to basics?