To take further in year 10 requires a passion - a passion very different than that required to take methods or specialist.
To take further in year 10, you don't need extraordinary maths skills. You don't need to constantly reign in as champ during your high school maths career. Hell, you don't even need to be able to do basic algebra for the most part.
But, you do need to love what you do. You need to be able to look at data, and relish the idea of discovering if the results have a positive skew. You need to get excited when somebody asks you to figure out if there's a net increase over time. You need to experience joy when somebody asks you if there's a correlation between two events.
Most year 12s can walk into further, and use their experiences in year 11 to fuel their drive into putting the work required into the subject to walk out with a 40+ score. You're different - you're not looking into the face of your future, and you don't have the crushing memories of VCE in your mind as you walk into the subject.
You may keep saying that you're just like them - that you're as excited about your career as they are, or that you've experienced pain in your maths exam scores before. But until you truly live the life of a year 12, you will not understand what they're feeling.
However, you have one advantage over them. Over those students who take further because they need some maths, because they feel maths is important, or even because they want an easy 40+. You have a joy and love of the subject, and it's that joy and love that will carry you into the top 8%. If you cannot tell me with 100% confidence that you can take further out of pure love and joy, I cannot say that you are ready to take this subject.