Your legs look quite far forward, as you were saying. Id suggest shortening your stirrups a hole, it should help bring your lower leg back. There should be a straight line going from your ear, to shoulder, to elbow and finally down to your heel. I like how you have your weight in your heels in the first picture, keep it like that but try thinking of getting your knee to point down to the ground, it'll help your leg aswell. I have the same problem with the "chair seat" but I think I've cracked it now lol
Also, your arms are too straight in the first picture, the "imaginary straight line" I talked about before will also help that, try to relax your arms to you have more of a natural bend in your elbows :) I also think you need a little more contact on the horses mouth (in the first picture) but bending your elbows more should fix that too :)
Apart from that, I think you look pretty good :)
Gotta say, beautiful horses too. Loveee the appy.
I wish I had one