I'm not trying to be mean, but I would really like to give you some tips that will help. (Especially if you go to a show for equitation, but it looks like your a jumper.)
1. You suck your stomach in, therefore, your chest bends forward. I can see that you are trying to pull your chest up, but your shoulders are also rolling in, make those shoulder blades close together to where your chest is out and your shoulders are back.
2. Your hands need to not rest near the horse's withers. I would like to see them up about 4 to 6 inches up his neck, and with your body closer to the horse. I would also like to see more loose rein, you are restricting your horse from jumping normally.
3. You seem to be standing up in your stirrups, you need to press your heels down and bring your leg forward, squeeze your calfs and hold them there.
4. Also, your stirrup needs to be one hole shorter, or maybe thats the correct length, maybe its the angle. Don't jump ahead of your horse, or thrust your body to get the horse to jump, he will jump by himself, stay with him.
But overall for an amature, you have a nice position =)
Good luck! Keep me updated!