Northwestern ED

I’m currently a junior at a relatively challenging private school. I have a sibling who’s currently a freshman at Northwestern doing pretty well. My main question is how much does sibling legacy affect my chances?
I have a 3.65 UW GPA (low but I’m hoping to bring it to a 3.7 at least), challenging courses, probably a 2200 SAT, and a decent amount of ECs (JV/varsity volleyball, social coordinator and president of youth group, tennis, science olympiad, various volunteer clubs and about 60 hours). I know I’m in the lower tier of students, but what are my chances?
Please comment on the effect of sibling legacy especially if you know from experience.
Thanks!