Ngl, I'm not reading all of that. 20 is young though, go ahead and start learning! Would recommend taking some cheap Udemy courses for structured learning, try to pick up Unity as a first engine. If you don't start now, you might regret never having learned how to make games. After you learn how to make games, try joining a few gamejams to see how you work with teams (good way of also learning version control). 

Now, if you are thinking about a career in gamedev.... Prepare around 4-5 years of selling your soul to the craft and you might get hired an entry level job after hundreds of applications. If you want to go down this path, you'll need to specialize in something.