As I was attempting the night night method, I immediately went to partial hanging, of course that didn't work either. So my very next thought was to do exactly that. Knife in the neck. Exactly the same thought process as you. Survival instinct is a fucking bitch and instead out of frustration I slashed both sides of my neck. Obviously wasn't deep enough but i bled for hours / days. Now sporting some rather unsightly scars in a really obvious place. I completely understand your frustration and desperation. I really do. This method may not work for you. I don't know. But I hear you. And it fucking sucks.
I can only say, and you won't want to hear this, but perhaps researching other methods may provide more success. Obviously that doesn't help you right now with your undeniable pain.