I think you have huge potential! You have an awesome seat and once you lower your stirrups a bit, you'll sit like a rock and be able to use your legs more effectively. You are doing a good job of sitting back! Most people, including myself, like to lean forward into that hunter posture. Your toes are pointing forward and your legs are wrapping nicely around your horse. Some things to work on though for sure is your heels! You have absolutely no heel depth. You want to sink your weight through your legs downward. Looks like you are putting pressure on the balls of your foot. Next would be your head and neck. Look up, girly! Your horse's head won't fall off, promise!
Keep up the great work and I can't wait to see more pics of you and your gorgeous horse!
Opportunity is missed by most people because it is dressed in overalls and looks like work. ~Thomas Edison