I’ll be able to tell you how it all turned out within a month, but your stats sound very similar to those of my oldest son who applied to UChicago ED this year. His unweighted GPA was a smidge higher than yours and his ACT a smidge lower, he had a few more APs (3.6, 34, 10 APs by end of junior year with 5s in most), but his pattern - Sophomore grades are what drags his GPA down - is similar. If he does get in, I suspect his ECs will be what made the difference. He has some very unique and ECs; I’m his mom and still can’t believe what he’s done with them - the biggest risk is that colleges won’t believe they’re legit.
The regional UChicago rep said that once an applicant is past a certain base threshhold - which she wouldn’t elaborate on - then higher grades or test scores don’t help. In other words, once they believe an applicant is qualified to benefit from the education, the selection process moves on to what other characteristics the applicant has, whether they’re a fit and what the applicant will contribute to the school. Since the highly selective schools don’t disclose what the GPA threshhold is (and it probably varies by school and rigor of course schedule), there’s no way to know if a 3.5 makes that initial cut or not.
If it would be helpful, I can let you know after 12/19 if my son was accepted and can tell you more about his ECs at that time as well.