Lower leg needs to be more firmly under you - as you sink more weight in your heels, push your lower leg forward so it's anchored close to the girth in your two point. Shortening your stirrup 1 -2 holes may help with that and closing your knee and hip angle, you look more as if you're standing up in your stirrups than closing your angles in correct two point.
Agree with the chicken wing comment, and also with the comment on the looking up and relaxed flat back. Like your release as well, appropriate for the level or horse and rider.
Cute horse with a nice attitude.