I dunno if I'm understanding you correctly, but why do you have to disclose anything to anyone? It's your ADHD and it's no one else business why you have extra time or not. You don't have to explain why you have extra time for assignments to anyone. If anyone asks and you feel compelled to say something, just tell them you and the teacher/professor talked and worked out something for you to have some extra time. If they continue to push the issue, just tell them it's personal and/or it's something between you and the teacher and do not wish to talk about it. There's no need to go into details if you don't want to.