You guys do look good!
In the videos- jumping.. Someone mentioned that you jump a little ahead of the motion, which is true, and because of this you land hard on your horse's back, especially after the last jump. In your last photo, (its hard to tell because of the angle) it looks like you are putting weight on your toes rather than down the back of your calf to your ankle. Because you put weight on your toes, your heel came up- and if she refused you'd be on your head! :-p (I know first hand because I used to brace with my knees and put weight on my toes when I got nervous and still do occaisionally) The photo is beautiful though!
When you jump concentrate on stretching your calf down to the heel and gripping with the inside of your calf muscles... Also try not to anticipate the jump, that is where you get jumping ahead of the motion.. if you have to, half seat a few strides out and keep your position until the jump- until you learn not to anticipate as much.. Also keep your half seat a stride after the jump so you don't land hard on your horse's back..
Your cantering video looked good! It was a little hard to see, the only thing I saw is that you come up out of the saddle a little bit each stride. You want to try to sit as deeply and quietly as possible, you don't want any air between your butt and the saddle!
Your mare is very cute! And my horse and I learned how to jump together too, he was 17 when he started. Good luck at your next show! And don't be hesitant to ask the judge why she placed you where she did, you might be suprised to hear the reason why, and get some pointers for the next show!