For boarding school you take the SSAT, not the ISEE, which is for private day schools.
Each of the schools you mentioned is very difficult to gain admittance. Their acceptance rates are generally in the low-teens or even lower, and most applicants have high qualifications. Your chances are probably about average, which means, like those of the vast majority of applicants, they are low. If you are set on attending boarding school, you would be advised to broaden your net to schools with higher rates of admittance.