There are quite a few things you can do to ensure you're progressing and/or to help you progress:
1. Take a look at some of your older code bases from a year or so ago. You should easily recognize things you could have improved upon. In this case, you've been improving - regardless of whether or not you think so.
2. Work on project euler problems https://projecteuler.net/archives and keep doing them until they become too difficult to solve. Come back to those same problems 6 months to a year later and see how well you do. I'll tell you right now that the questions that were previously difficult will be much easier, and again, you've been improving.
3. Come up with a plan to improve your skills. Make a list of topics you want to explore or problems you want to solve and knock them off your list one at a time (for example, I feel like I don't know nearly enough about multithreading and concurrency, so that's on my list). I like to use trello for organization as it's nice and simple. https://trello.com/
Yes, it'd be a great feeling for you to be able to answer some interview questions, but I don't think that'd solve your problem in the long run.