So you go back to groundwork.
lead her around on the ground, on her left side with abridle on, right hand holding the reins at her throat and whip also in that hand for easy flicks on her chest, or put one in each hand so you dont pull on her outh accidently..
ask her to halt using voice and the reins..when she walks into you a short sharp immediate tap with the whip on her chest..make her stop, or back up if necessary. if shes fin on the ground and doesnt walk into you then fin, thats already a start.
You wanna teach her, to be more responsive to rein, and leg, and listen to your seat. technically you should be able to close you fingers on the reins and sit deep and they should stop..by squeezing your knees together, you restrict the horses movemnt, so you do that, when asking your horse to stop. sit heavy in the saddle and ask.. short soft ask..
if she doesnt ask a firm hold and soften, with your whole body weight..the soften is so important though or your horse will just fight..the horse makes the downwards transition on the soften, so don't hold..
LOTS and LOTS and LOTS of transitions work. Work on getting her moving off your leg, then stopping a 1/4 of a circle later.. onc shes mastered go, stop..then move on to left right, a whole re-trainging process..
Our basics are Stop Go Left Right, when something goes wrong with them, it's what you need to work on before you can go any furthur.:)