I would definitely try to get more education. If you can't afford it or it is impractical, you should at least read some books on your own. I used to think I was fully educated at 18, but I learned a lot at the university. Even the stuff I already knew, I learned in a new and better way.
While it may still be difficult to get that interview without a formal education, this will at least make it easier once you get there.
(Two places to start: Introduction to Algorithms by Cormen et al and SCIP (available for free online))
For the sake of anyone trying to search: That should be "SICP," short for "The Structure & Interpretation of Computer Programs." (There are several organizations that actually have the acronym "SCIP," so Googling that leads nowhere.)
While it may still be difficult to get that interview without a formal education, this will at least make it easier once you get there.
(Two places to start: Introduction to Algorithms by Cormen et al and SCIP (available for free online))