That must be really tough.
I dont know if you tried it, but why not not sleep at all during the day, completely wear yourself out (be very active, sports, etc, tire yourself OUT!!) during the day, and then when your family goes to bed, do so too.
The thing is, when you have completely tired yourself out, you have no energy anymore, and your body NEEDS rest. So does your brain (since it's been active for over 24 hours), and thus you're gonna need to sleep. You probably just fall asleep on the couch in the evening if you do this.
Important though is that you seriously step it up in the activeness. REALLY go over the edge here.
There is a catch though. This will work one time, but the next day, you will probably fall back to your old sleeping schedule. To prevent this, be just as if not even MORE active during the day. Push your body in order for it to be so weak and tired that it needs rest. Continue this for at least a month. Your body and brain will need to get used to this. You can slowly 'decline' in the activeness during this period of time, until you're active in a normal way (most fit people do sports 2-3 times a week, around 1-2 hours every workout). It'll be tough, but it's worth it.
You have a disorder, I haven't looked into it enough, so I don't know if it's a chronic disorder. If it is, this will affect the rest of your life. If it's not, as in, you can reverse it, then you should not worry. In fact, it's the mind that is our biggest enemy when it comes to sickness and disorders. Once we are certain we have a problem, whether thats a disorder or a disease, we can actually make ourselves even more sick. So try to keep that in mind.
I wish you the best of strength and keep me updated on any progress you make.
p.s. Here's one thing that might be some sort of comfort for you: you're in puberty. Every teenager that's going through puberty gets sleepy at a later stage than adults or children, because the hormone that runs this sense of sleep doesn't work as well for a teenager. Or more like, it works later than it does for an adult/child.
Melatonin - Wikipedia, the free encyclopedia
That's the hormon. Since you're in puberty, this hormon does affect you like all teenagers. However, yours obviously affects you more. It's quite possible that once you've gone through your puberty, you will slowly adjust to a normal sleeping schedule. Your life is not over, if that'd be the case.
Buuuut I doubt your life is over anyways. Try my advice. Unless you did it already and it doesnt work. G'luck!