I totally hear you. I started at 17, I'm 28 now, and I can 100% relate to feeling suicidal, empty, and just totally screwed into nothingness. The worst part about it for me is career. Adderall made me feel like I was getting somewhere, financially, career wise, etc., but now it feels like it was all just fantasy. I'm halfway through law school and taking a semester off because I screwed up my grades so badly during adderall withdrawal. I'm staying with my parents in Florida and working at my Dad's law office. Every day I'm plagued with this terrible anxiety/depression about wtf my life is about and where it's all leading. I have no idea if I have any ability to handle law whatsoever off adderall.
The only things that seem to help are
1) remembering that I could have continued on like this even longer, and dug myself into a deeper hole,
2) recognizing that I'm catching up on a ton of repressed depression/anxiety/hopelessness that adderall was covering up, and that, every time I just allow myself to feel it, I'm chipping away at the darkness,
3) going through this site,
4) going for a run first thing in the am. I have to promise myself that I will walk as much of the run as I want to. But getting outside and moving before your mind has a chance to beat you up for feeling so useless and dead actually does wonders for wellbeing throughout the day, and
5) majorly lowering my expectations. If I can get through this without making my life WORSE, i.e. by gaining a ton of weight, losing money, losing relationships, becoming an alcoholic (because that is so freakin tempting right now) etc., then I will have beaten something I could have died with.
I also believe in reincarnation, so from a spiritual perspective I always remember, I could off myself, or keep taking adderall, or trade adderall addiction for another addiction, but that would just be delaying the inevitable. I find a lot of solace in the spiritual text A Course in Miracles. I do it every morning even when I absolutely hate it because the days I don't do it just suck terribly. And the Course in Miracles talks so much about the inevitability of change. It also talks about how whatever you're going through is the absolute perfect lesson for you at the moment. So I just try to think, I don't understand why I chose this path, and this lesson, at this time, but I can't possibly figure any of that out. I just have to surrender to it. Because there literally is no other option. Idk if that makes sense.
This is probably really depressing advice. But point is you're not alone.