Very few people on CC are 'seasoned prep school parents/students’. Rather, most of us are eager, hopeful, and uninformed applicants.
I’ll give my opinion though. You grade areYour SSAT is below the average of PA and PEA. Especially, your math is pretty low for a school like Exeter. Your ECs are mediocre, with nothing really standing out, ie. there is no clear passion or focus (maybe writing, do you have any results from prestigious competitions?) Remember that most applicants have what they consider ‘great’ interviews; all interviewers want to encourage as many people to apply as possible. I don’t think these three schools don’t factor in taekwondo very heavily, I don’t believe it is a competitive sport for these schools. Finally, you need FA.
From what you have given us, I’d estimate your chances to be