Horse bolting, help!

Agreeing with lots of the above, rule out any physical or pain related issues first.

Don't up the tack or bitting with a horse that doesn't understand or respond to the tack you already have.
It just escalates the fight.
What she's doing is like all undesirable behaviours, simply evading your aids.

I'd take the noseband off completely. Find a simple full cheek snaffle and school a one rein stop and basic pressure and release to a rein aid until she understands the only right answer is to soften.
 
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