I don’t know if this will help at this point, but I would point out that a lot of has worked for you. You were admitted once, you do have very strong grades, you do have parents who are coaching you and supporting you through your education. Top 10% is excellent, regardless of whether it yields admission. Zoom out a bit and look at the big picture because I get the sense that you are hard on yourself for not fitting into a mold. But ADHD people don’t fit a mold and they may need to be strategic about getting what they want.
21 is not too late to study medicine at all. In North America, candidates must complete a degree before they can apply to medical school, so people don’t go into medicine until they are 22 or older. I know people in Europe who completed Bachelor’s and Master’s degrees before applying to medical school. There’s a benefit there in terms of maturity and in terms of general knowledge about the world. You’ll know yourself much better and that will help make you a better doctor. As long as you are doing something that builds towards your goal, I think you’ll be ok.
Studying a year of law isn’t a bad idea either. Doctors do have legal responsibilities, so you’ll definitely benefit from having a legal foundation to apply when you are actually a doctor. I think virtually any subject could be useful when you’re a doctor, particularly if you choose a subspeciality.
Don’t give up. You sound like a highly intelligent person, with a barrier to overcome, but with an IQ like that, I am confident that you will.