Hey, I'm really sorry to hear this. I understand how frustrating it is to not be able to find a death that is accessible and not super painful. I wouldn't personally recommend jumping. It is possible to live through a jump like that. And I've heard from people who haven't succeeded with that method who said that the second they jumped, SI took over and they instantly regretted it.
I know there must be so many parts of you hurting to be this determined to die, and I am extending the parts in my system who have that same pain to let you know that even the parts of you that are suicidal are appreciated, and I hope they can be treated with the kindness they deserve. You're strong for living this long despite it all. Even wanting to die is another form of protection, to protect yourself from the pain, and I believe that even making that decision requires so much strength and determination. I am wishing peace and reprieve from pain for you <3