It takes 2 to pull. You and the strongest bit in the world won’t beat a horse.
Try: placing poles before and after jump, tins of gymnastics (!!), walk/trot in walk/trot/halt afterwards, straight line halt after. If you straight line halt, do not give her any room to disobey you! You are the boss and if need be, run her into a wall, she has no right to be disrespectful. Working on it in the trot and canter prior will definitely help too
Try: poles before and after the jumps, walk/trot in and walk/trot/halt afterwards, straight line halts after jumps (make her stop and don’t let her disobey you, run her into a wall if need be, she doesn’t have the right to be disrespectful. working on it in the canter and trot too
You can try hauling her a couple of strides before and after the jump to teach her to be patient.
Try putting poles after the jumps so she’ll have to think about the poles after jumping