I agree with Dank, you need to reach out to your parents, and get help from those actually in your life. Tonight is actually my first time on DGZ in about 2 years because of how serious my depression was. I didn't reach out. I was forced to, and let me tell you that's not a road you want to go down. If you're like me, you'll deal with this for your whole life, and i really hope you don't have to, but in case you do, I'll pass to you some of the wisdom i've discovered from my journey to figure out whether I wanted to go through with suicide or not. These things wont have intrinsic value until you think about them for yourself and apply them to your life, but these are the things that will (hopefully) help you up the fastest.
It's Chemistry, so there is no reason to blame yourself. You can't, actually, because none of this was your choice to begin with. Sure, you may have done some not so good things, and maybe those things contributed to your situation, but ultimately, it comes down to your brain chemistry, and that is beyond your control.
If you drop out of school, or do whateve big changes you're thinking about, do so with only one thing in mind: Is this what the best, most ideal version of me would do? This thought may hurt at times, as it has me, but it's allowed me to make some really tough, pride destroying choices that set me back on the right road back to happiness. This is a long term thing, so stick with it, and make those tough decisions. They'll help your confidence.
Confidence is everything, and it is truly only given to you by yourself. It's tough to make sometimes, but even faking it eventually brings you back to it.
You may never have what you remember as "motivation" ever again. Your new definition of motivation will be about how strong you are to force yourself to do things that you don't want to do. It's very difficult, but it gives the most rewarding feeling.
Above all, trust that you are in the best possible situation for yourself, then strive to better it.
Good luck with everything, pal. It's a difficult road to visit. I hope you make it out soon.