you can always try going the direction she wants to go.
One; play the "ok, you want to go left game, then we're going left and left and left and le . . ." until she stops. Then, offer her to turn right and if she chooses left, then circle her left until she quits. Offer right, and again and again. Careful not to make her so dizzy she falls over.
Two; Try the game called "Cruising". You get on, give your horse a very loose rein and in an enclosed space like an arena, ask her to walk on. The rule is, she must walk, if that is the chosen gait, and she may go anywhere she likes but she CANNOT STOP OR CHANGE GAIT. You do absolutely NOTHING and I mean nothing until she breaks one of those rules. IF she stops, you may kick,cluck shush or whip her forward to the same gait. If she breaks gait, you may pick up ONE rein and bring her to the one rein stop, then drop the rein and immediately ask her to cruise on. She may go anywhere she wants , even if she stays in one corner of the arena , as long as she keeps moving. You may not touch the rein at all unless she breaks gait. NO babysitting. Only intervene if she actually breaks a rule.