I feel like her leg falls back because of her heel, so I totally agree with you that her heel has to be down more. Once you fix that heel, I swear, your whole leg position will change.In the first picture you have way too much foot in your stirrup and your heel needs to be much, much more down. Your leg is also falling back over the jump. Very dangerous, I would really work on getting a better heel and not putting as much foot in your stirrup. The stirrup should rest on the ball of your foot - not the arch, where it is in that first picture.
In the flatting pictures it appears as thought you're doing dressage. But if you're not, haha, you definitely need to work on your heel, it's nonexistant at the moment. Putting your stirrups up one hole would probably help. Although, your foot is properly placed in the stirrup for the flatting pictures.
Your pony is cute, a little ahead of the bit but that's alright for your level. He has a super adorable jump, although he's a little hollow in the back. Doing lots of gymnastics will help him learn to use himself better, and as your position improves he will find it easier to jump as well.
Your upper body while jumping and flatting looks okay (maybe arch your back a bit more over fences), I would just really work on your leg. Your toes are in, which is wonderful.
And remember, eyes up! ;D