Are you at an ongoing school or does your school end in 8th grade? If the latter, you need to pursue more options, but having just gone through it, I don’t recommend the ‘apply everywhere and see where you get in’ strategy. For city schools, the spots are very limited, Trinity is the only school with significant 9th grade intake and even there it is largely sibling/legacies/ultra wealthy families and very high achieving URM and first generation kids. We have found that you really need to decide which school you want and aggressively pursue it in terms of letting them know you want to go there, through your own letter as well as word from families already there etc. They all seem to care about the yield a lot, with HM maybe the lone exception.
Boarding school is much easier, if you are strong student with strong scores, you will have BS choices as a full paying applicant (this is doubly the case if you are a boy, since the city odds are a lot harder for boys with most boys’ schools ending in 8th/9th grade). The process of doing both city and boarding schools is very time consuming, however, between open houses, interviews, tours, studying for the tests and also still doing well in school and playing sports or any other ECs so I would strongly suggest you go your research and visit some schools in the spring to create a shorter list, keeping in mind you do need a ‘safety’ somewhere if your current school is not a K-12.