First of all, I do not ride hunters. I am a jumper rider and eventer. For the most part, I think you are a lovely rider. There are a few things I would tweak if you were a student of mine.
You have really nice leg position. But, you ride on the back of your calves. I would like for you to bring your toes more forward and keep contact more with the inside of your leg. This would make your leg even more secure and stable for when you are going over larger fences. We used to say that you are "breaking" too much at the ankles. This habit will make it difficult or impossible to ever ride with spurs as they will be engaged constantly.
You have a tendency of rotating your hands into a flat position (puppy paws/piano hands). Thumbs up!!
While many hunter trainers are still teaching the crest release that has the rider pressing their knuckles hard onto the top of the crest and resting their upper body weight on them...others train otherwise. Even George Morris hates the fact that he was instrumental in making this release the "norm". This release teaches people to prop themselves, instead of developing an independent seat. Also, if the horse needs rein, that release is unable to give it to them when needed. It can be pretty restrictive.
You are a good enough rider to work toward a more automatic release. Drop your hands a bit onto the sides of the crest, instead of the top. This will make your hands more responsive to the horse's needs.
I hope you realize I am being very nit-picky. You are a very talented rider and can go far.
You look very tight through your hips, especially in the trot photo. I have the same problem to the extreme, and every time I ride after I am warmed up, I stretch out my hip flexors because it really does impact my riding (and not for the better!).
While I think the automatic release is a great tool, I also think that it's important to know how to do a correct long and short release if you get to a messy spot and need the extra support, because it does happen. You seem to be too restrictive through your hands. Even with a crest release, it is important that any contact you have be soft and sympathetic.
Good luck at your show, I'm sure you'll do great!
So I can't help much as far as the jumping goes as I am not that good myself
^^but I can see a few things that can improve in the flatwork.
First try to sit back in your saddle and don't lean forward. Look over his ears and not half way around the circle . Try to keep you hands upright with thumps on top so that they don't falll inwards and be flat.
Try also to roll your shoulders back and have a deeper seat.
Otherwise you leg position is good and overall you are a neat little rider. Keep up the good work