are you talking about an undersaddle class? (based largely on your horse's movement) if so, it's very difficult to tell without a video... but i'm going to venture out and guess that she doesn't quite have the ideal movement. in the hunters the judges are looking for a long low floaty way of going with very little knee action. but just because she isn't an automatic hack winner doesn't mean that you shouldn't try and compete. if she goes around in a pleasant and obedient manner and the rest of the horses around you are on the same scale as yours, I'd say go for it. One of the horses I showed last year (and the horse I'm going to show this year) isn't the fanciest mover but we go in there anyways and have a blast!