Should I kill myself on my 20th birthday?

I'm not here to pass judgment, just help if I can. It occurs to me that it's possible that you have undiagnosed PTSD. If it goes back far enough, it would basically have rewired your brain chemistry along the way. Therapy and medication only ever really proved pointless for me too. I started doing my own shadow work with the help of various sources (Teal Swan's video called "Healing The Emotional Body" describes a technique that I've found extremely beneficial). I don't *know* this, because I don't know you personally, but I would guess that your body is trying to tell you something with the constant headache.