Take a few deep breaths there girl, you've got a nice horse under you - no need to be riding like a tin soldier!
Drop those elbows, just let them flop down so they hang by your torso. You should not be wasting any energy in holding your arms up. Imagine that you have weights tied to each elbow, just let them hang.
When you have no tension in your elbows, I guarantee that your forearms and wrists will also relax, and you will be able to start developing some feel through the bridle. At the moment, you have zero feel, the horse is hitting a brick wall with your arms so stiff.
Due to the tension in your arms, shoulders, there is no connection from the hind legs through to the bridle. The horse is in a false frame, holding himself with an arched neck, but I am sure if we looked at video of the ride, his back would be stuck with no swing. He is slightly on the forehand, his front legs are taking bigger strides than his hind legs to keep himself balanced. The front and hind legs should be stepping evenly.
At the moment, he is 'faking' the work and you might score well in a local pony club dressage competition because he looks 'pretty' and 'extended'. But you really need to work on losing the tension from your body, to help him lose the tension in his body.
Very nice horse, and I am being picky because I can see that there is potential there going by other photo's and video's you have posted.