I would say the main disadvantage you have is that she's been riding for 6 years and showing for a long time and you haven't. (Why is she showing against you?). The show wasn't "rigged", she just had the advantage of experience and a little future knowledge. The more you ride and the more shows you've done the better you get. You know what to expect and the courses get so much eaiser to remember. I can usually just glance over a jumper course once or twice and know it. And if I've done my homework (worked on the hard turns, worked on making my horse as adjustable rideable, fit, and used to jumping different things as I can) then usually I can do a decent job of it. Shows are not a place to teach your horse techniques, you do that at home. Rollbacks, bending lines, combinations, scary fences, etc. Shows usually have them so get good at them at home. Practice learning long courses and learning them quick. And over time it won't matter how much the other girl got to know the course or practice it. And as the jumps get bigger and the courses more technical, it'll come to bite her in the butt if she can't do the work herself.