It's like doing your homework in school - you've been taught a technique or style and you need to put it to the test in some sort of competition. An example would be someone that can get in 10 out of 10 first serves during a lesson but they habitually double fault in match play. You have to learn to carry your lesson game to the actual match and the more you compete, the sooner that will be. Just try my theory for a few weeks. Double the amount of match play you have now if that is possible.
Many people use their lessons as their only form of practice.
Try adding just a match per week. I bet you will find that not only will you improve faster but also you will learn your strengths and weaknesses better and get more out of your lessons. Then go to the pro shop and sign up for this Years club championships.