You should be a cross-major, and different schools have different definitions of this. I suggest you consult the school you want to take the exam. Some schools still have certain restrictions on self-taught candidates, so you must explain your situation and admissions office in detail when you apply for the exam, so that you will not be rejected while waiting for the second interview. Even if the school enrolls students across majors, it is generally necessary to try two major courses for the second interview. Your competitive pressure is relatively high, so I suggest you prepare well.