Hey Torgath,
This sounds like a real dilemma. It also sounds like you're alone a lot if you're on the internet too much.

The solution isn't simple, but I think you just need to get out more. Step away from the computer! Make a few friends and do stuff. At your age, getting as much exposure to different things (legal things) is essential to find what your real passion is. Maybe you encounter a friend that's really into drums and they teach you how to play. Unknowingly, maybe you play like you were born to do that! Maybe you get exposed to coding games or building stuff with your hands. The point is you do something with others, lots of others.

You haven't wasted 3 years. That feeling you have when you think about that time is a HUGE lesson. In the future you don't want to feel this way so it's a message to CHANGE. Something other than what you typically do all day has to change: drastically or slowly.

So commit to doing something different every day. And get back into studying because it opens up more doors. Work in some time when you're normally just screwing around. I'd talk to a school counselor about that. There are tricks to get back into studying and making that rewarding (dare I say, fun). The good news is that you were once at a place where you could study for 6 hours. Most students I know can barely focus on something for 30 minutes! What you have is practically a gift. Nothing is wrong with you, you just need to get a handle on the situation. Talk to people you like, create little habits that compound, and explore this amazing world (outside of the internet). Whatever you feel like right now, THIS TOO SHALL PASS.