HS student hoping to do postgrad medicine looking for advice

Hey, I'm currently in grade 12 in QLD finishing up my IA3's and starting revision for externals, my current subjects are methods, chemistry, legal studies, modern history, economics and literature, i am generally smart but i definitely did not apply myself in my first IA's so I'm aiming for a 90-94 Atar. There's a clear lenience to humanities but i definitely think medicine is my main goal or 'Plan A'. My current plan is to do a diploma of nursing while completing an undergrad online probably psychological sciences at Deakin cause it would help with my nursing and also medicine later, then moving to Melbourne working as an EN and hopefully getting into Deakins post graduate med school. my original plan was to do an undergraduate in international relations/poly sci with my plan B looking at a job in diplomacy or working for the UN but i want to focus wholeheartedly on medicine. With this i was thinking whether just doing a bachelor in nursing would be better because EN have no career growth but i was hoping to be in med school by that time. Any advice would be great, I've done heaps of research so i know post grad is mainly about GPA and GAMSAT but every time i feel set on a career path i find something else to consider. thank you!