I'm in a similar boat. I dropped out of uni for reasons (a bit of a story, I can tell it if you buy me a beer) and ended up making a career out of software engineering.

The main thing to do IMO is spend time building a network. A recommendation in the right place at the right time can open doors that would otherwise be closed to you.

School is an option, but the opportunity cost has been too high so far for me. Though doing a freelance PhD thesis probably wouldn't hurt.