I am only going to critique the picture :)
First off you are WAYYY over jumping and if the horse were to stop you would go flying off. Your heel is up causing your leg to slide back. This means that your base of support is gone and has caused you to be launched on to the neck. The horse is probably a little freaked out with a leg back by his bum. Since you have lost your base your upper body has fallen apart. You are much to far ahead of the motion. You need to let the horse push you out of the saddle - you cant jump for your horse! Practice, practice, practice on the flat before you continue to jump. If you ask MIEventer she will explain why your base is so important.