sorry I know I'm not pi, but I thought i could offer you quick answer.
I think you have a pretty good chance. There isn't really a cut-off about how many superiors you need to get it. It's all about how well you did against other people who did the test and how many people in your school did better than you (5% rule)
I got into macrob with 4 superiors, some of my friends got in with 3 or 2 superiors and other people missed out with 3 superiors. It all depends on how well the people in your current school did. My sister got 2 superiors and missed out on macrob and got straight into suzanne cory. But the school that we came from were super competitive, 3 boys got into melbourne high ( two of them got 6 superiors!!!) and 3 girls got in to macrob + countless others into suzanne cory. I wouldn't stress, I honestly think you have a very good chance, if not you should most definitely get an interview at the very least.
Good Luck!