Stirrups look too short, hips need tucked under (using your abs to do this helps keep your body elastic) and your heels need to come back under you.
The horse isn't carrying itself with any collection. I see a hollow back and short striding at least in the rear. With better self-carriage, the head will come down to a more natural position on it's own. Working on lots of quick transitions helps develop those muscles. As do things like quarter turn on the haunches, shoulder fore, etc.
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