I don't know your situation. I imagine you live with other people though. I also don't know too much about this method but I imagine it is easy to harm others using it. I know people seal the area they intend to use with tape etc. and put up notices to prevent other people from getting hurt. Some people choose to do this method in a tent I believe. Again- I don't know what's possible for you. I don't know what you're able to do without help. I would say to bear in mind though that it is a method that could potentially hurt other people though.
I'm sorry. It's awful that it's made so difficult. Honestly, you in particular stand out as someone who ought to be eligible for assisted suicide. I just don't unserstand why those around you won't help you.