I thought you had on an interesting feathered hat in the first picture...hahah! Anyway, I feel the need to comment on this thread as your horse is the SPITTING IMAGE of my friend's QH mare, Catey. Like, identical. Same build, same movement, same expression...so funny!
I haven't read JDI's post yet, but I'm sure that she's already given you some great advice, probably much the same as what I'm going to say! :)
I really like your position in the first picture - but thumbs up! :) You have a nice natural arch in your back, but you'll have to focus on keeping your back relaxed, as I think there's the potential there of overarching! In the warm up at the show, focus on letting your back muscles flex, but be elastic so you maintain that nice hollow area you have right now.
You may have a really good reason for riding in a Kimberwicke - and if so, ignore this section - but I'd love to see you do at least a little schooling in a D-ring or similar type of snaffle, even if you switch to the Kimberwicke in show situations. Training the horse into the mildest bit possible will increase the amount of sensitivity you have and thus the finesse with which you can perform. I'm not a huge fan of Kimberwickes as they combine a harsher bit with immobility - a preferable option, but of course much tricker to use, is a pelham - where you can use the snaffle-esque part of the bit and only employ leverage when necessary. With a kimberwicke there's only one setting.
Second picture, same - thumbs up! :) You're nice and level in your torso and shoulders - the stripey shirt would give you away if you weren't!
In the third picture, although it's kind of an awkward angle - I see a bit of Locked Elbow Syndrome. We're all taught to follow our horse's heads at the walk and canter, but a lot of the time the trot is skipped over. Last year, one of my trainers had me work on this - first she had me post the trot, and pointed out that I would lock my elbow in an effort to keep my hand perfectly still, and in return I would get resistance from my horse. So she had me sit the trot without changing my arms - even more resistance! The locked elbows actually cause enough tension - however minute - to make me tight enough that I bounced against the trot rather than flowed with it. Trainer had me stop, drop the reins, give my arms a good shake, and then pick up the reins with clenching anything. She had me trot, and told me to keep my hands over the withers but let my arms just hang from my shoulders. Because I was no longer set against her mouth, my mare moved forward much better and started seeking the contact. The moral of this overly-long anecdote? There is a very small amount of motion in the horse's head and neck at the trot, and we have to learn to follow it. It's trickier than the walk and canter, but once you feel it, you've got it.
Now, because of the angle, I could be wrong - you may have very elastic elbows! But just based off the picture, that's what I see. Your horse's head is in a good place, but her hind end isn't. It's right out behind her - so she's lulled you into a false sense of engagement while allowing her hind end to go on it's merry way. Work on those loosey-goosey elbows, give your horse her head, and get her tush underneath her. She has such a lovely neck naturally that she'll find it very easy to round over through her back and come into self-carriage once you engage her, and you'll find you don't have to pull on her mouth to get her there.
Next picture - same as above, with the whole engagement thing. I think this mare will be absolutely lovely once you're riding her back to front. Your position is essentially good, but you're overriding the front end and it shows a little in your equitation. I'd like to see you sit deeper in the saddle - get those seat-bones centered underneath you - pull your shoulders back, and let your legs fall a few inches further back. This will put you in an optimum position to push your horse forward, cue her from your legs, and get the coveted 'whole package.'
Fifth picture - shoulders back! Eyes up! Thumbs up! And if you're going to have more contact on one rein, make it your outside - you want to bend your horse with your inside leg, get her onto the outside rein, yada yada - if you use the inside rein to turn and flex, she'll just become wonky in her body and throw her weight onto her inside shoulder.
Sixth picture - same thing, really - thumbs up and driiiive your horse forward. In the seventh picture I like her balance, but again - the hind end is trailing along behind. If you find she gets more forward after a canter, incorporate it into your warm-up - while you're trotting around on a slack rein, throw in some transitions, get up in two-point and let her open up her stride, whatever. That way she'll be stepping underneath herself from the get-go. I like your upper body and arm position - to be nitpicky, I would have you slide your legs back so your calf aids aren't obstructed by the girth. It looks like you may be a little grippy in the knee; relax, sink your weight into your heel, and let your leg lengthen. In the eighth picture, same thing - only more so! Your gripping has propelled you a little out of the saddle her, and I suspect you began to lean forward to compensate and regain your rhythm. Lunge lessons would probably help you find your center of gravity and perfect your leg position. Your horse is also overbent to the inside - counterbending to the outside helps get those nice round canter circles, as it rebalances the horse. Although intuitively we all want to bend to the inside to get the weight on the outside shoulder, that unfortunately doesn't work. Counterbend when the balance or bend are compromised.
I can't see too much in the ninth picture - just the leg, again, and what looks like a bit of a resultant bounce. Also too much rein - as I've said, your horse needs forward now, rein aids later! :)
I see an offending inside rein in the tenth picture. I don't know if you've done any lateral work, but I'd suggest schooling a little shoulder-in, leg yield, and haunches in so that after a canter, when your horse wants to fall on the forehand and rush around on her inside shoulder you can regain your nice, bendy trot via your legs. Again, using the inside rein to fix the issue actually makes it worse - but if you can trot down centerline and push her into a leg-yield, she'll have to think about what she's doing with her shoulders. Same with shoulder-in - when you can move your horse's body all different ways at will via your seat and leg, you're well on your way to being able to achieve balance in any situation, without the inside rein!
In the twelfth picture your mare is hollowing through the back and resisting - be it because of the bit or a loss of balance, I don't know. I do see your leg coming up again, and with it, your body going forward, which unintentionally pushes her faster. If she's off-balance already, the resulting canter won't be too pretty! Sit tall, lengthen your legs - imagine you're dragging your heels in the dirt! - and half-halt, release, half-halt, release...if she needs it, down transition, whip out a handy leg yield or two, then pick up the canter again. In the last two shots, your horse is really overbent to the inside. We must always remember that for every moment of pressure, there must be an equal moment of release - so if you squeeze for a stride, you then give for a stride. Repeat as necessary, but never hold the 'squeeze' for more than a stride.
Anyway, I really like your horse and you're looking quite good - just keep schooling the fundamentals, and everything will really come together nicely. Good luck at your show! :)
And now, the men of the Second Armored Division with their famous close-order swanning about.