There are just a few things that you should start to think about.
Keep your eyes up! In some of the pictures it looks like you're looking down, you might not be, but anyhow... It's so simple but it really has a great effect on your body's balance if your eyes are on the ground. My instructors always said that you go where you look.
I'll go along with the poster above me in saying that you should focus on keeping your weight in your heels. In a few of the pictures your legs looked like they've swung back a bit. That's a very common problem, especially if this is your first time jumping this height. To be able to keep your weight in your heels better, I'd do a lot of work at the two-point. When I was working on that I would literally ride around WTC for 30 minutes in two-point (Half Seat/Jumping Position) It sucks, but I saw a huge change in my jumping position.
I actually think that your releases are adequate. You didn't seem to catch your pony in the mouth or restrict his movement, so keep doing whatever works.
Overall, you're looking quite good! Your pony looks great, congratulations-he's an adorable jumper.
Keep up the good work.