Question first, context later:

If I am a dedicated, self-taught programmer, always seeking top-quality books AND READING THEM, while successfully applying all that new knowledge into my current work, could I call myself (and offer my work as) a PROFESSIONAL developer? How limiting (or how common) that is nowadays?

I am afraid that, no matter how hard I study and practice, it could be too difficult to compete with "actual", college graduated developers, and potential employers might have doubts investing in an "undergraduated" person.

Now, context:

My former profession is from healthcare sector, then I studied mechanical engineering (quit in the middle), then I studied product design (master degree), and I ended up working (very happily) at an engineering company that manufactures medical devices.

For more than two years now my main activity in this company is software development. The devices contain software, and we gave up hiring software development (domain knowledge needed, too much communication cost).

My current company sees a lot of value in what I do, but I cannot afford the risk of depending on this single company for the rest of my life, you get it. But a lot of job offers require some minimal formal education, usually a CS degree.

Fact is that I am sure this is my target profession, I don't plan to go to another area, it is a pleasure to dive into books that normal people would consider unreadable, but I'm 36 years old and can't see going back to college as a viable alternative.