I may be misreading things, but it sounds to me like you're saying "I have x diagnosis so I'm allowed to do y." It may be better to accept "Because I have x I do y and that's my problem, I have to deal with that/remedy that/quit this course". A diagnosis is never an excuse. It might mean your diagnosis is interfering with your studies - that means you can't do the course. Just because the reason you can't do the course is your diagnosis doesn't mean you have a 'license' to 'misbehave'.

I worded some things poorly in this post, especially the last sentence - I hope my meaning is still clear. (English is not my first language. (And if you're about to call that an excuse also - I'm accepting that my problem might interfere with my ability to make myself clear and I'm not saying "You should understand me even though English is not my first language." I'm accepting the consequences of my problem - namely that you might not understand me.))