So from what I can see is that your heels are up, your hunched over, and your hands are in your crotch. Try to stretch your heels down, bring your upper body up, lift your hands, and even maybe push them forward.
When you are just riding try getting the correct position at the walk; heels down, hands up and forward and not touching the horse, and upper body a little further back. Then once you've got the hang of it, try it in the trot.
"You know, for as long as I can remember, I've had memories." ~Colin Mochrie