What to do to improve my chances for Stanford, Duke, Harvard, and a few others?

Are you first generation? Are you low income? (I’m pretty sure I know where you go to HS based in the info you posted.) If so, you may qualify for Questbridge which would help quite a bit. Pomona, for example, as a lot of QB admits. I agree that “all the Ivies” is way too unfocused and prestige driven, But I do think you have potential to get in some top schools so I hope you come back for more info.