Paths to mathematics/university/research while dealing with a few difficult situations
Universities typically demand qualifications, which you don't have. You could get some: You seem familiar with advanced areas of mathematics, perhaps you can study some revision guides, teach yourself whatever you need to know to get some qualifications. (I'm unsure which institutes you can enrol with in Australia. I presume such institutes must exist. They do elsewhere—not everyone follows the traditional route.) Alternatively, you could reach out to universities, explain your situation, negotiate why they should admit you without typically mandated qualifications. Perhaps you have someone who can help you, e.g., some staff member who happens to know an academic who is willing to help you navigate the system.