A Levels and APs

The best way to think about course rigor isn't actually the total number, but how you compare to people at your school. For example, different high schools in the US offer different numbers of APs, so you might have one student with 12 APs and one with 6 who both took the maximum number available to them, and colleges will look at them roughly the same (despite the big difference in number).

So if 3 A levels is the most you're allowed to take, you'd be on par with other people taking the most rigorous schedule available at their high school—which is basically what you need to be at (or just a little bit under) to get into very selective schools.