The sheepskin on your saddle is quite distracting, and I think the saddle itself is not fitting you quite correctly.
You are sitting in a chair seat, and the imbalance caused by this is forcing your heels up and for you to put too much foot in the stirrup.
I would recommend removing the sheepskin in case that is what causing your issues and not the actual saddle. From there I would focus on really pushing the leg down and stretching it around the horse's barrel so you are not gripping, but instead balancing to stay in the saddle. Finally try to use smaller aids which leave your leg long and enforcing them with a kick or a dressage whip. The horse needs to learn to go from a small aid which does not distort your position.
Otherwise your upper body position is good and I think fixing your leg instabilities will allow you to balance better with your upper body. Remember to always keep your shoulders back and down. The visual of touching your elbows to your hips is useful.
I'm sorry, my mind is all over the place right now, but I'm going to do a very quick critique as you seem like the type of person that appreciates a critique, whether it's long winded or not! :P A few things I notice right off the bat: - You are collapsing your inside shouder and ribgage; this blocks the horse's own ribcage and shoulder. - Close your hands around the reins, and drive your horse INTO the contact; right now it looks as though he's evading by dropping behind the bit - Be sure to keep your hands on the correct side of the horse's neck; in photo 3, especially, you can see how you're crossing your left hand over his wither. If bending or turning are problematic, creating an open hand and getting a hold of the shoulder and rib is going to be much more effective than crossing your hands over the wither. - Your stirrup has slid "home" against the heel of your boot; think of sinking your heels down, and keep that stirrup under the ball of your foot. I would also like to point out that you and your horse seem like a very well-matched pair, he's quite the looker! Your saddle looks really comfy with that sheepskin!
The previous posts covered you pretty well so I will cover the horse.
Basically the contact is missing or uneven. He is not being pushed into correct contact and in some pictures he is on the forehand. He is stiff through the neck and as a result is not coming correctly through. In fact he is coming up short in stride...and he is not that long in the back that would physically account for the lack of a good open stride.
If you have a coach they need to be looking at getting this horse to more fully open up and be less "stuck" in a headset.
You need to push your heals down and keep your stirrup on the ball of your foot. To keep your horse moving, your shouldn't push with your body...you should sit up tall keep your shoulders back and push with your legs, and keep some contact with the horses mouth. And keep your legs long and try not to bring your leg back to hook him with the spurs...instead try and bring your heal up and just hook him and bring your heal back down.
I noticed in a few pictures you are crossing your hand over the withers. Try and use the withers as a guide and not let your hands cross over them. If you want to move to the right, pick up your right hand and push with your left leg, don't steer with both hands.
Another thing is, I was always taught to hold my reins with my pinky finger around the inside of the reins. So the reins come in between my ring finger and pinky finger. You just have a fist around the whole rein. If there is a reason you are holding them like that, then forget I said anything about it.
Also your reins are uneven, the inside rein looks like you have less contact than the outside rein...try to have even contact.
Just remember to sit up tall and keep your legs long and underneath you and your shoulders back. Sink your weight into your heals.
I really like how you have a nice bend in your elbows...your horse is beautiful.
I think everyone pretty much got everything but I agree that you need to keep your heels down and the stirrup on the ball of your foot. You need to keep you thumbs facing up.I looks like your hand movements are quite right. In one of the last pictures it almost looks like you are neck reining. You are also slouching, keep your back nice and straight and then everything will align right. When you fix all these problems I think that your horse is going to move much more fluidly and stretch his stride out even more. Your horse is just gorgeous by the way.
The first thing I noticed is that I really like your upper body. I like how you are sitting back and not leaning forward. That said, there are still some things to work on. You shoulders are uneven, meaning you are twisting your upper body to sort of "point" in the direction you are going. Ease your inside shoulder back and sit up taller.
I do like that your hands are up instead of down and having locked elbows but the rein contact is all over the place. Theirs either no contact, contact or one rein tighter than the other. I would shorten your reins a bit and make sure you have even contact. There's no need to hang or pull on his mouth. He looks like a nice guy who isn't going to need a lot of head correction or jerking of the reins. A nice even contact is all you need..
A major yuck I see is your leg and stirrup position. First of all, you need to slide that stirrup out a little more from your foot. The stirrup should be positioned so that the outside bar is touching your pinky toe and the inside bar is against the ball of your foot. Having this angle allows your ankle to flex with more ease and can slightly help keep your toes facing forward. As someone else mentioned, I would recommend taking that sheepskin off the saddle pad to get a closer feel. I don't think your stirrups are too short, I think you just need to sink your weight through your heels. Not pushing, but let the energy flow through your legs and down your heels, not your toes or the flat of your foot. Right now you are in a chair-seated position. Bring your legs back a bit and I think once you practice riding with no stirrups for a while and the concentrate on keep your heels down, that might solve the problem. The problem with chair-seated riders is that that they aren't really using their legs for anything, hence the heels up. If they are doing anything with their legs, they've usually got a pretty hard grip on the horse that is just tensing up their legs and not helping their position.