I totally have a horse that jumps like this. I know you'd probably love to slow down and be a bit more controlled but the more you focus on control, the less you have.
This is a case of a rider that's doing a good job on a nice horse with the wrong mentality. Horse sport is such a mind game.
You need to first of all stop focusing on the fences. If your horse gets a bad spot, they're barely at her shoulders and they fall down. She's smart enough that she'll figure it out and if she's at all like my horse she hates touching rails and will do anything to avoid them.
Think about soft heels, soft elbows and driving your shoulders to your hips. You are strong and soft in the wrong places. Let your heels come down and stabilize you, let your shoulders come down and stabilize you and then your arms can be soft and allow a release. After that, count. I ride a jumping course counting 1 2 3 4 over and over again. Regulate the horse's stride with your weight and legs. Sit up, relax and she'll slow down, I promise. Put your leg on and lighten your seat - there's your forward aid. Just maintain a rhythm and she will find the spots.