I agree with above posters.
Fix those hands, thumbs up! Shoulders back and lift up your chest, remember not to be stiff. Relax your seat. You look a bit stiff through your hip, in one picture you've fallen back on your butt. Remember to stay on thse seatbones. Don't let that lower leg slide forward, send your weight into your lower leg and heel, but don't squeeze too much or else you'll pop back.
Look up and where you are going. Looking down will put your horse on the forehand. And he is already.
Give your horse more leg. You are riding mostly with your hands, his head is on the vertical but his back is not engaged. Get him to lift his back up and move with energy into guiding hands.
Forward, forward, forward!!
Use your seat to prevent him steady, don't pull with your hands and force him into a stiff frame.
Stiff hands equals stiff horse.
Other than that, you guys look great! Your horse has such a pretty face!