Others have commented on the legal/professional issues but I feel I should comment on the technical issues. I was in the same position as you were at one point so I have some insight others may not have.
When I was 15 I had extensive knowledge of computer programming as well, at least I thought I did. When I was 16 I published multiple Apps to Google Play and even made a few websites. I definitely felt that I was ready for a software developer job so I was in the same boat as you.
But you do need to keep in mind that watching videos, reading books, and practicing code only gets you so far. There is NO substitute for actually taking University level classes. The amount of technique I learned in just 2 years of University made what I knew before-hand look like nothing.
So what I'm saying for your situation is that I'm sure that you are quite skilled, but being able to do software development and do it well are two incredibly different things. You need to be sure that you are to the level that a professional would be before attempting to get a professional level job. In the professional workplace software developers are expected to know A LOT about what it is they are doing. And it can get hard even for people with CS degrees.
I know that it is hard to imagine that there are things you can still learn about software development when you already know so much, but take my word that there are things that you probably haven't even considered. Algorithm Time Complexity, Optimization techniques, industry standards (BIG one), and how high-level langues are translated to low-level byte code (seems unimportant but can really improve your code) are just a few of the things that go into being a software development.
So all-in-all id suggest an internship or similar where the point of you being there is to learn, as opposed to keep up with professionals is the way to go. And don't take my answer the wrong way. I'm not saying I think there is no way you are actually good, I'm just saying you most likely are not YET ready. I may be wrong, but my personal experience tells me you may get in over your head at a real software development job at 15.