englishjumper16, what grating on me is the tone of your post. it almost says 'oh, this pony is kinda broken, so instead of fixing it i'm going to get another one'.
i mean no disrespect at all by my statement, but it is so prevalent in today's society to just 'get another one' instead of fixing what is wrong with what one already has.
another thought is that you get tense in new places, and that transfers to your horse, causing the bucking. relax :)
do you have a trailer and can you take her to various places yourself? by that i mean your parents would drive, unless you have your license and are experienced with towing trailers.
take her to various arenas in your area, ask your other local stables if you can come during times of low/no activity at first, and build up to where you are bringing her places when it is quite a bit busier. don't even bother riding the first few times you go places, just walk her around, maybe lunge her a bit if allowed. this will help build up her tolerance for the hustle and bustle of your typical horse showground, if that is where her bucking issue is stemming from. hey! see about taking lessons from a qualified instructor at a respectful stable, trailer your horse in once a week, etc. this allows a second set of eyes (the instructor's) to see anything that may be triggering your horse that you may not be seeing. might be good to start with private lessons, working up to semi-private (just one or two more riders in the arena with you), to group. group lessons are kind of the equivalent of a flat show class, where multiple horses are in the arena at once. i think this would help your horse a lot if it is an issue she has with the level of activity at a show.
other ideas are to play loud music at the barn at home (or wherever you board), hang up lots of fluttery stuff (flags, etc). make your horse's home seem like a crazy busy showground on occasion. then it won't be so much of a surprise to her when she does go to a show. it's all about desensitizing! :)