I'm not MIE but... I have to say... there is something... I just can't quite put my finger on it... But. Your form, or maybe your horses conformation... just, something doesnt quite look right... might just be your tack though...
You know, I think it might be your riding boots... they look a little worn out... Are they making you uncomfortable to the point where you get slouched over?... hmm... I agree with Farmpony... somethings just not quite right
I see a nice solid lower leg, and I love that you are on all 3 points of your seat. But......I really dislike how your heels are not doing their job. They much anchor you!!
Your upper body is nice and tall, wonderful - but your hands are much to low. How do you expect to aid your horse to remain off of his forehand with hands like that??? All back end, remember - back end.
On that note, your focus on working that back end is greatly admired! I like that you are focused on working that back end, and leaving the front end alone. I love that you're looking up too.........and where is your ASTM Gas Mask Mr??? Very unsafe to ride without your certified and approved gas mask! Naughty.