My weighted GPA is 5.2 (yes I know my weighted GPA is weird its just how my school does it) and my unweighted is 3.96 (I am a junior right now) and I have had straight As for the first two quarters of the year and I am taking 3 APs and the rest are honors classes (except math). I am the president of the feminist club at my school and im also part of a lot of other clubs (the biomed club and a club that helps freshman around) I am also in Dance National Honor Society and National Honor Society (soon) and I sing in a choir over the holidays and I teach STEM to underprivileged kids and etc. I take dance and also biomed and I play softball and I played basketball until the end of my sophomore year. I have taken 3 years of spanish (and I plan on taking 4). I haven’t taken the ACT or SAT yet but I am not really sure how I am going to score because I am not the greatest test taker but I guess I am going to try my best. I plan on getting around a 27-30 best case scenario. And I plan on going Pre Med. Of course I know that these schools are reach schools for me but I wanted to know if it is even worth applying to because my test scores might be below average compared to others but my GPA would be relatively good. And also I dont know if this even helps that much but my grandmother went to Barnard so I have alumni in my family. Anyways, any response helps 
Overall, your app looks like its on the right track. You’re going to need to do better than 27-30, though; a 33-34 would put you in a solid position. As always, the pre-med track is going to be extremely competitive. Focus on improving your STEM-related extracurriculars and try to get some awards/research: they’ll significantly boost your admissions chances.
One a side note, a grandmother alum should help, but I’m not really familiar with legacy admissions at Barnard specifically.