This question was asked 2 days ago. Here is the thread Late app
Take a look at some of the single sex schools. If you are a girl, look at Emma Willard, Miss Porters, Westover, etc. Take a look at Dana Hall in MA. If you are a boy, look at Salisbury, Avon Old Farms, Trinity Pawling, etc.
I'm assuming you are in the MA area. You might call Pomfret, Berkshire, Northfield Mt. Hermom and Cushing to see if they have openings. If you want to venture a little further, give a call to Kent, Gunnery and possibly Loomis. Even a little further, call Blair Academy and the Masters School. If you are willing to go beyond New England, there are many great boarding schools that might still have openings because many applicants focus on New England.
I don't know that any of these schools still have openings. As I'm sure you realize, this year was very competitive. When you call, be sure to let the schools know your special talents in case they don't have them on the waitlist.
If your family can afford it, an educational consultant who specializes in boarding school placement could be very helpful, and will probably know which schools would be a good match for you and might have some openings.