I started programming late into highschool as well, and only a TI83 at that. My first rendezvous with network/gui programming started in college (though I was a CS major). Now, more than half a decade after graduation and working in silicon valley, I'm hacking on more serious projects like writing operating systems. I don't think starting late has affected me negatively too much. Just keep at it, you'll reach your full potential before you know it.