What a very pretty boy! I don't know much about National Show Horses and how they work, but I can do my best to help you.
You are on a good start, but if I were your Coach, I'd tweak a few things to help you be more effective of a rider.
The biggest thing that screams out to me, is his false headset.
Yes, it "looks" pretty, but it isn't real. And when it isn't real, it is very unfair for your horse physically. You are now allowing incorrect muscles to form, and are not creating a rounded, balanced mount.
You really need to get him to open up, move under himself and track up. You need to help him lift his back up into your seat and get him engaged from the back end.
The whole picture must be there, not just 1 piece of the puzzle.
Right now, your riding front end first, instead of last. You should be riding back end first, and front end last. When you get the more important factors of the picture in place first, then the last set of the puzzle will fall into place *True Collection*
Do you know anything about the Training Scale?
Your form isn't helping either. Yes, at first glance you look "pretty" just like your horse, but you aren't being effective. In order for your horse to be effective, you must be there first.
First, you need to get your tail bone under you, straiten your lower back and activate that core. Without your core, you are not effective, nor are you balanced.
As the "Great and Late" Sally Swift explained it -
Imagine you have a bowl of water in your belly. That bowl of water represents your balance and effectiveness. The moment you hollow out your lower back, all that water gushes out your front end. The moment you roach your lower back, all that water gushes out the back.
You don't want to spill that water - because if you do, you've lost your effectiveness, your center, and your balance. So - you need to correct that, and start using those tummy muscles.
Secondly - there are times where your legs are in the dashboard, and then ther are times where your leg is where it should be - which is under you. I think you are losing your balance here and there - but you need to engage that core and your seat to help obtain your security in your tack.
Now put the two together - your seat/core and your lower leg - you can then get your horse moving correctly. Right now as I've already said, he's going around uneffective, not using himself correcly - so by you activating your core/seat and leg - you can get him moving forward, opened and under himself.
Thirdly, you need to correct your arm and hand position. Right now they are far too low, and your going around with "Puppy Dog Paws". In order for your seat/core and legs to be effective, your hands must play a part in the play as well.
Shorten your rein, pick up your hands, close your elbow angle - get your elbows at your side, and get your thumbs up. Now - you are able to not only lift your horse UP, but you are also able to aid him to get off of his forehand, and onto his back end.
Also, you are now able to contain that energy you create with your seat/core and legs.
That's the most I can offer at this point, I have to get my Chocolate Chip Cookies out of the oven. :) :)