You should build a portfolio! Don’t worry about building projects for others or for pay at first, just make some projects that you’d enjoy making. Some very common (maybe cliché?) examples are building a Twitter clone and making a tip calculator. Throw it all up on github. Make a personal website (it doesn’t have to be super-beautiful) that can showcase your work. This is an example from a Codecademy software engineer (who was himself self-taught): http://www.jon-samp.com/
You need to be able to show what you’ve built with code and speak as to how you’ve built it in order to be able to make progress in your career. Certificates and things can help, but ultimately employers only care about what you’ve built and how.
It’s a long journey, but making that portfolio of projects is an inevitable step in your journey if you want to pursue this track seriously.