At the risk of being accused of being "pro life", that isn't my intention. I just don't want you to end up a lot worse off.
I'm simply going to suggest you find something else. Your carotids are not close to the surface as many people think - you have a significant amount of neck muscles in the way. For hanging to occlude the carotid arteries the neck has to be compressed by about 20%. That's a lot of muscle and tissue to cut through and from what I heard from a friend who is a cutter, muscle is extremely tough to cut. Go try to cut a raw steak from a weird angle and imagine how tough that'd be. Unless you have an iron will, you will most likely just end up with significant lifelong injuries, possibly breathing and eating through a tube, and possibly having to learn sign language or use a electronic voice box if you or your family can afford it (they aren't cheap). You will end up with all the problems you have now, but only a million times worse.
What is close to the surface are jugular veins. Veins clot and collapse after a little over a pint of blood is lost. That won't work.
Back in the day there was an infamous video of the Russian-Chechnean War called chechclear or something like that.
Some Russian soldiers are caught by Chech fighters (might be the other way around can't honestly remember). Anyways, in the video a soldier is on the ground and his enemy proceeds to shove a combat knife in to his throat, over and over again.He's not trying to slice, like cut off his head, but proceeds to stab the guy in the throat. All I can say is it's pretty damn horrific - the attempts to scream and gurgling sounds I wouldn't even wish on an animal, much less another human being. And the dude does NOT lose consciousness right away. I'm sure plenty of people here have seen gore videos, but it's a horrendous way to try to die, IF you even do. Tbh, I don't see how anyone could have the willpower to continue because you literally have to work at it. Over the course of several minutes.
I know there's a popular misconception that Avicii died this way. But he didn't. He was blackout drunk and made surface cuts with a broken wine bottle all over his body. Alcohol thins the blood and promotes bleeding. He died from bloodloss over a long period of time from many surface cuts. He had a very high blood Alcohol level that it was said without it he most likely would not of died. It was more the combination of things than just the cutting, which, from what I heard he wasn't a cutter or in to sh, rather he was depressed, got shitfaced drunk, and in a stupor started thrashing at himself when a bottle accidentally broke. I had also heard he was on rohypnol but don't know how true that is as I don't believe it was ever officially reported. Was never a fan of the guy, just felt for him as a fellow human being who was clinically depressed.
I realize we are all different and on our own journey but please don't do this. There are much more reliable and peaceful methods. For a couple bucks and a trip to the grocery store, you could have something every bit as peaceful as Nembutal. If you have access to Amazon or Walmart or ebay, even better. Search the forum for N2O.