Alrighty lets get started. so you lean forward from the waist up when you canter and attempt to canter especially. this accomplishes nothing but putting more weight on your horses forehand and make is harder fro the to pick up that canter, so sit up nice and tall, your back is straight which is good news so just sit up. also elbows flop out every now and then not major problem. toes flare out. i know squeezing for the canter. (I teach lessons, I hear everything ;)
but there needs to be a more reactive horse underneath you. Ask tell demand is the system i use with my students. ask the horse politely with a squeeze and kiss or cluck. tell the horse; light little bumps that get more and more firm each time or every other bump not like a full out kick. Demand; crop. yes the ugly "C" word. most of the time even carrying the darn thing will make that little halo pop right out. once you get that horse going give it a bump every stride or every other. ESPECIALLY in those corners.
Also give your horse a better approach if you not showing in jumpers then you don't need to worry about cutting seconds from a time. especially since this is your first show. use that inside leg and angle for the center of the fence more.
especially on the 2nd video with the white picket i was oh oho ho okay they made it. wasn't even sure you were going to take the fence. if that was a young inexperienced horse 99% they would have run out.
Also pick up those reigns a little you need a solid contact with their mouths not pleasure reigns. and move your horse up a little more before the fence not just with speed but also impulsion (power from the butt) get her on the bit and push her forward. might need to do some dressage to nail that one down\
Don't worry, just ask my students, i am very picky in normal lessons and before a show my pickiness is times 4. so i just go hard on the riders that i know got the stuff! good job and good luck!!!!!
Hardest Thing About Riding Is the Ground!