If you need experience, then go out and get that experience
The simplest thing you can do is go out and build more things and apply to more jobs, even ones outside of your area. (You can always back out of any job if they ask you to relocate, but its great to say “yes” when they do ask regardless, just to get further along the process)
Now I say “go out and build more things” and there’s a lot of ways to about this. The easiest is think of something, anything to build and go out and learn how to build it. Since you already have made a full stack app from scratch, maybe do it again, but add more new technologies (socket.io?) frameworks (instead of React, maybe use Angular?) or methods (use test driven development). Just build something to learn something. Odds are you will run into issues (I’m sure you ran into some when you did your first app, which is totally normal) make it as impressive as you can, and add it all into github so you can “show it off”.
Now building something for the sake of building something is fine, but you could go out and find potential clients and ask them if you could do free work for them. For example, you can go to a local library and say your a junior developer and would like to offer your services to do something for them as volunteer work. Odds are you can help them somehow, just be prepared to do something you might not want to do, or let someone else make some decisions for your (the library staff will give you the requirements, just like actual work )
Obviously you can go do freelance work and get paid, but you will have to spend time and effort getting those jobs. Your welcome to try and you might get some jobs, but if you take the “free volunteer route” there is a lot less pressure, and you can probably get a lot more flexibility on the project, and provide more input. Most freelance work is mainly about getting work done for cheap, or very specific jobs for cheap.
Finally, your welcome to learn more CS at any time as a developer, but it’s hard to show that you learned the topics without a degree, and as such I wouldn’t recommend focusing on the idea learning just to learn, you learn to do, and the best way to learn is to do!, so you can kind of see it as a cycle haha.
PS. Overall it sounds like your probably past the basic concepts, since you could have 0 idea of computer science topics and still be able to build a full stack app haha. Having those fundamentals is a great thing to have, since they impact almost all kinds of development you do.
Goodluck, keep building