Hey bro, I'm not entirely in the same boat as you, but I'm also Aussie (I think you're Aussie from stalking your profile?), also ADHD, and also trying to get into med school! Some of the advice in here is really good but I can see a lot of other people don't really know anything about the process and how hard it is. Just because you feel like a failure right now doesn't mean you can't be a doctor in the future! My friends who are already in med school all say that maybe 10% of their class is mature age, and this is from like three different med schools in Australia. If this is what you REALLY want then it might take some time - but it is achievable.

Your current degree is not gonna do anything for you when applying. You need to go on and do a Masters (which might not be the best idea if you're already struggling with undergrad) or just pick a different undergrad course entirely - one that you have a chance at doing well in. GEMSAS only looks at the last three full-time years of your study when they look at your grades, so you can effectively wipe your current record if you can go on to do something else.

As you've been diagnosed with ADHD you have HEAPS of options available when it comes to equity services at uni, and you need to use them!!! If you're anything like me, a lot of your Fs come from handing things in late because you didn't have enough executive function to do the thing 😭 there's structures in place for that! My uni in Melbourne lets me hand anything in two weeks late, no questions asked and no penalties, as long as I email my coordinator and let them know what's going on. I also get rest breaks during my exams so I don't have to try and focus on a four hour exam at once - I can go step outside for ten minutes and stretch or lie on the floor and just take a mental break. These accommodations have been LIFE CHANGING for me and I wouldn't have half a chance at getting into med school without them. You're not a failure, your brain is just wired differently!! You need to work with your strengths.

Another thing I would highly recommend is underloading. I know it's hard to admit that you might not be as smart as the others in your class, but underloading means you can actually focus on the subjects you are doing instead of wildly flailing around with 4 at a time and inevitably neglecting one. The only times I've been able to get all HDs (or As or 4.0s or whatever) in a semester it was because I was underloading. I was never able to do four subjects at once and do well in all four.

Your ADHD means that you work great under pressure and you'll probably ace the GAMSAT when you go to sit it :) I scored in the top 10% on my first try and barely studied lol (but I would never tell my friends that!) I was considering actually studying and then resitting it but I don't have $500 lying around and my grades are actually ok apart from my first year when I was figuring everything out, so I'm applying this year and seeing how I go.

If you ever have any questions about anything or just want to rant, feel free to DM me! I'm more than happy to try and help you work through whatever barriers are stopping you from getting the piece of paper you need. I have never met someone with ADHD who wasn't truly brilliant, you just have to figure out how to prove that to neurotypical society!