You have done well to take full advantage of the opportunities your small school provides. I encountered similar issues coming from Eagle River, Alaska. This will reflect better than someone with more AP/Honors but, say, a lower class rank or GPA. While it is not necessary, I believe if you apply for a major (especially if you will end up applying for the pre-med track), colleges like to see why your interested in it, or how you’ve grown and explored that interest. Again, not necessary, but you could always mention it somewhere in one of your essays, since it’s not shown anywhere else, like the extracurriculars. Speaking of, they reflect strong musical passion as well as talent, and NU is sure to appreciate that. I would recommend you choose to include that in your application, and if you get the chance, indicate that you would like to continue them in college. Focusing solely on your SAT score, it is not strong enough to guarantee entrance if admissions were done on test score alone. I would /highly/ recommend taking both the SAT and the ACT once more this coming fall (you will still have time to do ED). It is even more impressive if you can send in 2 impressive standardized test scores, and your ACT score, while good, still has room for improvement. Additionally, I believe SAT subject tests are required for the bio/med fields, so sign up for those early. Final notes: You will be competing for admission with the other students in Chicago and Illinois, which means you will probably have a lot of other students attending NU from similar backgrounds and for similar reasons. So I would put it to you to do your best to stand out, both in your essays and in your interview. Good Luck, and remember, I’m not a college counselor, just a NU student using my experiences as a guide. So do not treat my word as law. Good Luck, I’d love to see you next year. 
(sorry for the essay-length response)