Firstly, shorten your stirrups a couple of holes.
Try riding with jodhpur clips, tuck your jods into your socks or wear half chaps/gaitors. From the photo, your jodhpurs are riding up your leg which creates a section of bare leg which is uncomfortable and may be making you pinch with your knee to keep your lower leg away from the horse.
Next practice your two point position, sinking down into your heels and keeping your leg forward.
Don't throw your upper body forward so much and sit taller, this should keep your leg back.
Press you hands into her neck just passed the wither for your release.
Try to jump with straight elbows, this will fix your release and keep your back tall.
Think of almost standing up in your stirrups, for this size jump you hardly need to move your bum out of the saddle so keep it closer.
Don't throw yourself forward, think of the horse gently lifting you off the ground. Let your body follow the movement gently. Nothing should be sharp. It should all be flowing and smooth, like a song.
Hopefully this hopes.
Abigail, Riding Coach