Would this disability be something to bring up in your PS if it had nothing to do with your decision to pursue medicine/you don't acknowledge it as a "disadvantage" even though it probably is...if that makes sense?
or is this something to bring up in your interview if it comes up somehow (very doubtful)?
You will be required to complete/pass a physical to start medical school, and sign that you can perform the basic functions of the job with/without accommodation. But this is all after you've been admitted - it's illegal for schools to discriminate admission based on disability. (That being said, it doesn't mean it doesn't happen. For example, if a school were to read a statement that implies the applicant still has significant health problems, the school might worry the applicant might not be able to finish med school on time or at all. So that's why the advice on here for people who DO want to discuss personal medical problems is typically to be vague and focus more on you and your personality than the details of the medical experience.)
My advice would be: it is YOUR medical problem. There's no reason to bring it up anywhere unless you want to. It's not like it's this big gap the schools are going to know about - they will only know if you tell them so feel free to not tell them, if you don't want this to be part of your app.
(If it is a physical disability that will be apparent when they meet you in person and you wanted to address that if it was awkward or something, you could always deflect by acknowledging that you have this disability, but then changing the topic like "But what REALLY got me interested in medicine was..." Stating that you are doing well now might be good too, like above. They can't legally ask you for details and I doubt most schools would get really pushy if you answered vaguely and changed the subject.) I know a lot of people might be like "Oh but it's medical you should put that in your app!" or you might feel that it's typical for people with medical conditions to write about them for their medical school PS. But you have to write the best application YOU can and to me, cheesy as it is, that includes being true to yourself. Sincerity, IMO, leads to better writing and better defenses in interviews since you can talk about the subject at length. So if your answers to "why do you want to be a doctor?" or "How do you cope with stress?" don't include talking about your health condition then don't try to force it. As much as it is true for many people that their own medical conditions led them to be interested in medicine, there are probably just as many people who have medical problems and weren't affected by them that way, nothing wrong with either one.
With regards to the "extenuating circumstances" essay, I don't really know the best answer without having more details so you might want to talk to someone you trust with that information IRL. I would generally say that if you don't feel that it was a disadvantage, don't write about it. I would lean towards including it if there was an obvious defect in your app, but if you don't think it's noticeable than that's just another reason not to write that essay.
Side note... if you need accommodations, those are granted after you are admitted as well. There is no need to bring that up during an interview and I think most would advise you not to do so. If you are really worried make an anonymous call to the office about their accommodation procedures or something like that.