There is ALWAYS something to learn when it comes to horses. If you think about is, 10 years with horses isn't that much, especially since it sounds like a lot of your experience has been in a lesson situation and not the daily grind of feeding, property maintenance, etc.
I do think one of the best ways to learn more, and learn it quickly, is through working student positions. It's hard to find one that suits your specific needs, but they're so incredibly beneficial. When I was 19 I was a working student for a year for an upper level eventer in Maryland and I learned more there in one year than I had learned in 14 years of riding, showing, and lessons twice a week. There are so many little things that go a long way when it comes to horses, and our knowledge is constantly growing in the industry. Not only that but there are multiple ways to get things done, and everyone thinks their way is the best.
Anyway, what I'm saying is don't be discouraged! There are people that have been around horses and working with them for 50-60+ years and the good ones will admit that they STILL don't know everything. It's all about the desire to learn and having an open mind!
"Always be yourself. Unless you can be a unicorn. Then, always be a unicorn."