What would your ranking be, roughly? Are you in the top 10% of your class? Do you know what the average GPA of your high school is?
Have you looked at your school’s Naviance to see what the rate of admissions are for applicants with your stats? However, when looking at Naviance, remember that private prep schools also have a large number of legacies for “elite” colleges, which may skew the numbers a bit.
You should also speak with your counselors - many GCs at private prep schools have good relationships with AOs at “elite” colleges, which also helps in admissions. Your GC will also likely be able to give you a good estimate of your chances to the “elite” colleges on your list. In general, GCs at private prep schools are really good at helping students figure out the best places to which to apply, and what they would need. They will definitely know better than anybody here.
A very large part of the advantages that private pre schools have in college admissions are their GCs, so do take advantage of this resource.