Should I use a disorder I have as an excuse to get away with something?
What does having a disorder have to do with it?
Because no one ever forces me to do something I don't want too if I mention I have the disorder.
I see what you mean, but you shouldn't use your disorder to make excuses for things. Tell the truth for your actions instead.
I think it's fine to use it since that's what the doctors want me too.
Unless your doctors excuse is actually to keep you out of certain activities, then you shouldn't abuse it. Those notes were written under specific guidelines and should be followed.