Your hip and heel are not align. Your leg is too far back. Your seat is too far forward witch has you leaning on your horses neck. This will make him off balance. He is just trotting over this cross rail so a nice easy 2 point is all you need. Good luck!
Like others said, your lower leg has slipped back. If you want an idea of where it should be, next time you're on that horse, stand straight up in the stirrups like your were standing on the ground. Find your balance to where you do not have to hold your horse's neck to balance. Then, without changing your lower leg position, sit almost down in the saddle to where you are just hovering over it. That's the correct jumping position. You look like a nice match for your horse. I'm sure you'll do great.
The last one is the best I think. I think that you need to go with your horse as you seem to be a little in front of her. I like your release. I don't think there is anything I can add that hasn't already been said.
Thanks everyone! :) this is all awesome advice and will use all of it, I have been told that I should put my thumbs flat more in my twopoint and less like how I have them when im trotting or cantering while not in the jump! What does everyone think of this? :)