Strangely enough, I would say that a course is probably the slowest way to learn the engine. It’s because they have to cover a fixed load of stuff, and you’re probably more interested in other aspects.
You’re also never going to see a utube tuut that gives you everything you need, you always have to hack and filter from those things, take only what’s useful.
You have to remember the engine is and expansive software suite, and a lot of people could never get anywhere with it, so anything you’ve done so far is good.
My advice would be to just ask you what you really want to have happen on the screen in front of you? What would be really cool? How can you make that? You need to be driven to reach that.
Then start taking steps towards it. You have to realise that these will be very small steps for quite a long time, but they will get bigger. You will find you niche with the engine.
Don’t be put off by coming up with a load of ■■■■ either. Just look at it, figure out what’s wrong and improve or do it again. Just start to get some things working, and build.