I think you look good! Gorgeous horse, he looks like an all around athlete
You do need to sink into your heels more. Try lots , and I mean LOTS of two pointing on the flat athe the walk, trot and canter. If you are still having trouble, stand up and let your weight drop into your heels. Then sit down again, but focus on keeping your heels where they are.
Part of the trouble is that you are pinching your knees. Instead, open your knees and let your heels and lower calf anchor you in the saddle. This will also keep your leg from sliding back.
For your release, it's not horrible. If you don't feel confident in doing an automatic release quite yet, pick a spot about half way up his neck and grab mane untill you get accustomed to it, then jkust slide your hands up his neck.
look up a bit more, that should help you too.
Your horse has a very cute jump, you too could go far! And sorry for the novel,