Looking pretty good girl. One exercise you can try on you own - since it looks like you're pretty independent out there - is called up for two, down for one. It's a position self check. Takes some practice and getting used to, but when you get it right you'll know your position is exactly right - ear, shoulder, hip and heel aligned - at ALL times. Your equitation can only truly be correct if you're balanced. So try this:
Instead of your normal up, down, up, down rhythm - you'll still sit for one beat, but you'll stay up out of the saddle for two hoof beats, then sit again for just one beat, then back up again for two, and so on. The trick to starting in proper alignment is to keep your lower leg back (ankles relaxed), hips coming up and forward, and upper body tall (your upper body shouldn't change positions between being seated vs. rising). I would highly encourage the use of a grab strap until you get the hang of the coordination and balance. You'll be surprised at just how off balance you really are.
Also when you get this exercise right, your horse will automatically slow in the trot. Proof once more that the seat, not the hands, control the tempo and length of stride.
Don't give up on this exercise. It'll highlight your every weakness. All the more reason to practice it till you can do it with no hands! When you can, you will truly be balanced. The " equitation " you're after will be a side note. Promise.
Ps - your stirrups are a hole too short, no more. And keep your elbows a little closer to your sides. They get a bit stiff in your efforts to keep them "quiet". Truly quiet hands come from relaxed and mobile elbows....
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