You said you're 21; are you in college? (I am near your age too) If so, there might be more resources on your campus than you think--anonymous helplines, student groups dedicated to mental health awareness, etc. These are some things that several universities have.

Either way, as difficult as this sounds, try opening up to someone you really trust... or even someone you may not know that well but who seems like a caring, nonjudgmental person. Who knows, maybe that person will open up back to you, and even if they're not going through self-harm but something else, it's always good to have a buddy who can empathize and look out for you.

I'm sorry if that wasn't as helpful or comforting as I intended--I'm very very exhausted and it's quite late here--but I just wanted you to know that I can relate to you, you're not alone, and I wanted to reply you back as soon as I could. Excuse any incoherence; but bottom line is you're in my thoughts! (and prayers if I were religious but I'm not really so mainly thoughts )

- AJ