I'd go online and just google your diagnosis (like Searinox already said). Find the one or even more link(s) that most feel like what you're feeling. Let them read through that and then maybe have a little QnA session? I know this really might seem stupid, but this helped my mother understand my situation a lot. She did some reading on her own and then we just sat together and she got the opportunity to ask questions. You'll have to keep in mind that people might ask wrong questions (like "Why don't you just go out and be happy?" or "Why don't you just do anything even though you don't feel like it?") because they don't know any better. Just listen to their questions and try to tell your point of things. In my opinion, that's the best way of making anybody see how you feel and actually understand you. I hope that helps ;)
