Hi there, I am not a dressage rider so can't be much help there other than to say that you all look beautifully turned out to me, especially your horse. I do jump, so can offer a critique there. It looks as though you do not have enough weight in your heel but are rather standing on your toes which has resulted in you pinching with your knee which then acts as a pivet and allows your lower leg to slip back behind the girth. This in turn has caused your upper body to be far too far out of the tack, essentially "jumping ahead" of your horse. This results in putting your horse off balance and putting you at risk for a tumble should he stop or perhaps add a stride in at the last second. In an ideal world, you want to be able to draw a straight line from your hip to your ankle so that the line would hit the ground right underneath the very middle of your horse--- your butt would be out of the saddle, but still over the center of the seat (not in front of the pommel!). To correct this, I would do a lot of work on getting those heels down on the flat---perhaps doing some two-point at the walk and trot to stretch those heels out. As you start jumping, stay aware of those heels and be patient, wait for your horse to jump---don't try to jump for him :) Jumping without stirrups will also really help strengthen your leg (which already looks pretty solid) and keep you from jumping ahead of your horse.
Your back is nice and flat and it looks like you are looking ahead which is good. Your release could use a bit of work although is better in the second photo than the first. You typically want to move your hands several inches in front of the martingale strap, pressing your hands down and into the crest for support. In the first photo, your hands appear to be "floating" above the neck and perhaps slightly catching your horse in the mouth, although in the second pic, your hands are looking better, actually set on the neck for support and a nice loop in your rein, giving your horse his head to jump.