My DD loved Summer STEM. She’d been targeting USNA since 7th grade and applied unsuccessfully to STEM twice before finally getting in before 11th grade. She’s glad she persevered because it helped cement her desire to attend USNA.
Funny thing is, while she enjoyed the STEM stuff, she mainly loved just being on the Yard among mids. NASS was going on at the same time, and whenever she heard or saw or passed by that bunch, she wished she was with them instead. So this also reinforced her desire to attend NASS the following year, which she did.
One way or another, it seems like a win-win. You may decide USNA isn’t for you but realize how much you enjoy STEM. Or vice-versa. Or neither. Or both. But just learning that will pay off in the coming college-application process. And as long as you remember that going to STEM — or not — has zero bearing on your chance of receiving offer of appointment, all should be good.