Go get a degree. Preferably ABET accredited. Im in literally the exact same boat as you. Years of self taught experience with no degree (a high school dropout, no less) but constantly apprehensive about "hitting the wall" in terms of career advancement. The best decison I ever made was to start taking math classes at the local community college, and eventually start working on an engineering degree. You will be amazed at how much you didn't know you didn't know. Its quite hard to swallow your pride and sit in a classroom full of teenagers, feeling like an idiot fumbling over undergrad math problems. But once you get over that it's totally worth it.