Fight it, fight it, fight it! If you accept the prognosis, it will surely come to pass. I believe in mind over body. Please think this way! Praying for a full recovery.
I intend to let the docs do their best. However at nearly seventy years old I wouldn't take a transplant away from aw aw from a youngster. I have a beautiful 24 yo niece who is down to 52 breathing capacity. She needs and others need it worse than my self.
Seeking a 3rd opinion was mentioned. As one who has seen the limitations of modern western medicine, my advice to all is that seeking the opinion of a "non traditional" or "out of network" (doesn't bow to the insurance companies) doctor might be worthwhile.
Tough news, praying the docs can get a handle on what ails you.
I'm most impressed with your attitude, esp. the fact your putting others needs before your own.
Hang in there, don't knock yourself out doing so but please pass on whatever news you can.
Additional thought and prayers outgoing for your niece.