I think most developers assume that the more years they write code, the better they become. I have a very different measure for whether you are really bettering yourself.
Ask yourself this, and answer honestly:
With every new project you successfully complete, do you feel that the previous project was not done as good as the one just finished? Do you have an urge to open that previous project and bring it to the same standards as the latest project? Or do you feel that both projects have been created equally?
If your answer is the latter, I am sorry but you are not growing. No matter how good you are.