I'm also a teenager. 18 actually.
I know what you mean. The internet is wonderful but sometimes it makes me go crazy looking for stuff. The most frustrating part is that the information I want is probably all out there, but the problem is that I don't always know where to look. Sometimes you find some real nice golden nuggets hidden in some 30 year old application notes or from some mysterious website. But finding it is the problem. This doesn't just apply to teenagers of course.
Lately what I've been doing is stocking up on electronics books. I don't exactly have the time to read them right now, but for me, books are the key.
There's something about learning off a computer screen that just doesn't work for me. I like printed text much better. Books help me focus and retain better. Also, I think the quality of writing and the content of books tends to be better than some explanations you might find on the internet. There are of course many great resources on the internet, but a quality printed publication seems to work the best for me.
I'm not sure if sitting in on college lectures would be good or not. I've watched some of those MIT/Yale lectures and though the teachers are typically brilliant, they seem to focus too much on math for my taste. I'm pretty good at calculus, but sometimes I just think it's unnecessary to constantly employ it while you are trying to teach something that might be difficult even without the calculus and advanced physics.
This Christmas I treated myself to the Art of Electronics (1989), Design of Modern Transistor Circuits (1973), and Designing Audio Power Amplifiers (2010). I haven't had too much time to read but what I have read has been top notch. My girlfriend thinks I'm a complete lunatic for a.) buying books for Christmas and b.) buying engineering reference books. But anyway, I've found them to be in depth and very complete without too much BS, which is what I like about them. The college books I have read seem to be good information but you have to weed it out of all of the theory. Theory isn't bad, but sometimes it's just like "give me a break! just tell me what I need to know!".
I'm not sure where you are on your electronics "journey" and how much you know. This is just my personal thing. Books books and more books. The internet is great but you can't beat some good ol' books.