I'm sorry that you are so ill! That must be awful for you especially with the chronic pain. I hope you have good doctors and medications to cope with all of that. Pray to God and tell him how you feel and what you want to have happen. Also remember it's God who has the final answer as to when you die. If you do die, then you will be up in Heaven without any pain or discomfort and you will be the right weight. My husband died a month ago and I know he's up in Heaven and out of pain and discomfort. I know we'll both be in Heaven together eventually.
However, God may just heal you also and you may have a healthy long life. Just pray and leave it up to God and try and enjoy your current life as much as possible. I will say a prayer for you also.
PML