Dude, I haven't even met you face to face but I agree with the doctors. You DO display remarkable immature qualities for a boy your age. Whether that makes you a momma's boy or not, I dunno, but....I can see it too.
Maybe they don't know why your lung quit working. Maybe they think that they can best treat you by quitting wondering why it happened and by moving onto treating your symptoms. You need to lose weight in order to have any quality of life....but you already knew that, didn't you? The healthiest way to lose weight is to watch what you eat and increase your physical activity. I know how hard that can be when you have a condition that makes it difficult or painful to exercise, but I can guarantee you that once you've dropped a few pounds you'll feel so much better. Just watch what you put into your body, and start walking more.
I wish you all the best, Lucas. Good luck with your weight loss quest.