Alrighty. Just a few minor things!
1) In the third picture, your heel is up, and your toes are pointed out. Sink deeper with your heels, and rotate your ankle so your toes are pointed forward. This will also help your leg from sliding back!
2) In the video, your horse looks like he is rushing the fence a little bit, keep motivation going, but don't let him rush. When the jumps get higher, he's going to need to suck back so that he doesnt go flat over the fences.
3) You have a beautiful release and a nice flat back!
For without a horse, i could not fly.