I really feel for your situation, it is a tough one! I’ll try not to repeat too much that others have already advised – all of the advice posted in this thread is spot on!
Your parents view point is coming from a place of worry, so maybe you could find a psychiatrist that specialises in ADHD, and once you have built a rapport with this psych, you could bring your parents along to a session.
I’ve only been diagnosed with ADHD recently, at 34 years old. For most of my twenties, I flirted very heavily with substance and alcohol abuse. I was highly impulsive, did a lot of things I regret and largely wasted many years. I also struggled with depression and anxiety, even during periods where I would get my act together, exercise and avoid alcohol and drugs. I was honest about alcohol dependency during my diagnosis but I wasn’t very forthcoming about my history using drugs.
I’ve found my ADHD meds to be immensely helpful with my day to day functioning, mental health, anxiety and clarity. I’ve tried both short acting and long acting with no desire to abuse my medication in anyway. My preference is even for the extended release formulation.
Given the above and everyone else’s great advice, I would find a psych with a better understanding of ADHD, and I would try to get them to help your parents understand better.
All the best, I hope you work something out!