I don't remember what I did on my 17th birthday, but I remember how I made money.
If those whole images are yours with spray paint I'd say ya got some talent.
If you can do these quickly you could make them on the spot, espcially characatures that sell at fairs and festivals, and make some cash. I think the fumes would need to be controlled though, for the event people to allow it.
When I was 16-17 I was in my last year of high school and only had to take half a day of classes, and the other half I worked in some program the high school had for career planning. I actually worked at a man camp in the kitchen at a power plant that was 10 miles out of town. Had my own room there, for getting away when I wanted, with a new stereo and various other things that you are probably into, from sone of your poster indications. That was about 30 years ago though
I also did part time house construction and learned how to build houses back then. Did alot of dry wall work when we weren't building.
After I graduated, at 17 years old, I joined a union 10 days later, and was making more money than I'd ever had. Had to lie about my age to build the nuke plant, not thrilled about nukes, but it had a standing call for 50 men a day.
I had buddies that worked on the Railroad up there in montana, and they made good money doing it. Last I heard they paid pretty well on the railroad. Don't know that' I'd do it as a career, but it's a good start, if you can get it.
I also did what one of Phils family did, way back then. Not recommended in these times.
Check out the art shows, and maybe somebody will buy your stuff. Don't totally rely on other artists trying to help, cause you're competition for the money to them.
They have a nice art and craft festival every year down by the university here. In a place like the university area you could meet alot of other artists that may give you ideas, and whatnot.
Before you know it, you'll be out on your own, so get a leg up