Ok, take a deep breath, let it out, now shake your entire body. You are very stable up there, but a bit tense. I would like to see you come to your seat bones a little better, pull in through your belly button, and flatten your lower back. Press out through your rib cage and let your shoulders fall into position. Bend your arms a little more, you are riding very much out of your shoulders instead of your core. Your legs are nice, steady, and secure, but I would rotate the thigh bone through the hip to the inside, so your knees and toes are pointing forward, so it is more like you are standing over the horse than sitting on top of. As Boxer mentioned, this is easier in a dressage saddle, but can be accomplished in any saddle, just may feel a bit awkward.
Zeus is a cutey, with a lot of potential. He is very focused on you and seems to be looking for your guidance. As far as traveling, he looks to be a bit of a handful, litteraly, you must have some serious upper body girl! With that gag bit, he is relying heavily on your hands for balance. I saw several shots with a gaping mouth, he seems to be bracing and balancing on the bit rather than just having a gentle contact. He is very congested in the throat latch area, which shows that he is pulling in his lower neck and breaking at the pole instead of releasing the lower neck, stretching through the topline, and falling into a nice contact with the bit.
Moving onto the midsection, he is using his abdominals well, but still falling a little heavy on his front legs. We want the horse to lift through c6 and c7, the last of the cervical vertebrae, and pick up the front of the saddle, bearing more of the weight on the hind legs. He looks a little tight in his lower back and slightly disconnected through the hind end. He is trying his heart out though and is getting pretty good extension.
Sorry if I'm being too specific, please don't feel over criticized, you are a beautiful rider with loads of potential and it looks like you are very young still. Zeus is also looking to be quite the impressive horse that is just hung up on one little glitch before he can find his place on his own.
For a long time, I had the ability to get on anything in hold it together in an aesthetically pleasing way, however the next person to get on that horse would have a world of trouble. That is why I started to learn that instead of relying on myself to hold the horse together, I need to teach the horse how to hold itself there. That is when all of the small signs started to jump out at me, the small catches that prevent the horse from achieving balance. I have had great help along the way. Keep up the good work!