I think it depends on your goals and your interests. A friend of mine is self-taught (mainly front-end programming, JS, HTML, CSS). He started in his 40s and w

I think it depends on your goals and your interests. A friend of mine is self-taught (mainly front-end programming, JS, HTML, CSS). He started in his 40s and work in a completely different field. He developed surprisingly good programming habits by himself, but he's strongly lacking in some areas, compared to people who followed a conventional CS education. For instance, he has little knowledge of algorithms: he can't write a merge sort, assess its complexity, or work with dynamic data-structures. These are the type of things that can be hard to figure out alone. I think it's worth investing some time on this. There are tons of resources, e.g. a few good Coursera classes. You can also focus on different layers of the software stack. You've been working on the front-end, but you can have fun with things like system programming (e.g. writing a UNIX shell in C), or a compiler for a simple programming language. I personally enjoy doing programming projects from various universities. There are tons of cool projects at all levels.