Well, Lu, I think you are miles ahead of a lot of other riders. There are way too many recreational riders out there who spend years, if not their entire riding lives, doing just what you were doing. You recognize the problem and want to improve your skills! That gets a thumbs-up.
Try not to judge your progress by what you see others doing. I know that can be difficult. If you feel you are having difficulty with something, ask for help. Sometimes it has helped me to just watch other riders...
I hesitate to say this but here is something that worked for me...I mentally ride...visualization. For me it's hard to watch events and not "ride" with the participants. Personally, I find a cross-country course really exhausting! : ) I'd be willing to bet there are lots of others here who do the same thing. If you take what you have learned and visualize doing it, it sort of gets your brain to train your muscle respones to do the right thing. Another thing that might help is put a saddle on a solid stand, tie some reins or rope to a post (or whatever) and imagine the arena lesson...how you should be sitting, leg cues, etc.
All of this is no substitute for actually sitting on the horse but it might help with some of the basics and make you more comfortable.
If you ever find yourself in a fair fight, it's because your tactics suck. ~ Marine 1SGT J. Reifinger