leela Current Y11 student, keen in medicine as welll!!!! I will suggest in Year 10 next year, try doing a VCE biology or chem or methods in advance (if your school allow to do so, if not, do it outside school , perhaps Distance Education / Victorian Virtual School?)
You have more say than me 
) on what kind of thing that you like to explore in these topics. There are lots of free and good quality resources online for self-exploring for interests. (I benefit the most from Libretexts when searching concepts in textbook) Even if you don't enrol in those classes in advance, you can still go on your own pace. Self-learning is a required skill for a future med student like you)
However, one important thing to note is that, try to engage in as much as different activites as you can. Year 9 is such a great time to learn about things in life (sports, arts, music, or getting a part-time job )other than just studying. What I heard from a number of current medical students on Open Day at Monash and UniMelb, is that they all enjoy their life entering med school. Make friends, engage with people and communities in real life. All will help you become a better version of yourself, and eventually a doctor that you want to be.
Interviews are just all about your personality and the feeling that you bring into the person about you. You need to be trueful, and act like a doctor that you would expect when you see your GP.
Start UCAT prep next year perhaps?>>>>
Go to open days at Monash? Ask the students about this, they have better answers for this.
Good luck
((((( well done everyone