I am self taught as well. Most of the material is available online, Park Tool’s website has great information on how to fix just about anything on a bike and YouTube will cover the rest. I volunteer at an organization that accepts donated bikes which we fix and then giveaway to charitable organizations that give them to people who are in need. I have recruited several people who want to learn how to work on bikes to come volunteer their time and I help them learn. Mostly what it sounds like you need is a healthy number of subjects to practice with. Many communities will have bike co-ops which also provides a chance to learn with some expert help.

Not to say that the schools are not good but I have never met a mechanic who has gone to one, so unless you need the certification for some reason I see them a bit of overkill.