First off, your position is ver nice and solid. There is one issue that is causing some faults.
Your stirrup position. Your stirrup iron is too far back, it must be placed closer to your toe. Right now, you are unable to sink your weight into your heel and flex your ankle. Because of this, you are unablem to anchor your legs at the girth- and your leg is slipping back. The incorrect iron is also causing stiffness in your lower leg.
Once you correct your iron, all of your lower leg faults will correct themsleves. You will find it easier to keep your toes in and your leg will not slip back.
Also, your release is too high. Place your hands a few inches lower on your hroses crest, I should not be able to see your outside hand. You are at the point where you can begin using an automatic release, your losvely horse will benefit!