I just posted this in another thread but it applies here, too:
Look at the Music Major forum here at CC - especially the essay pinned at the top called the Double Degree Dilemma, which talks about the different ways to study music (by itself or in combination with other subjects) in college. Here is a link to that: http://talk.collegeconfidential.com/music-major/1948726-double-degree-dilemma-essay-written-by-david-lane.html
Be aware that “double majoring” in music plus something else is often actually a double degree because, depending on the university, the two majors are often in two different schools within the university and you have to fulfill all the requirements of each school. So you might be earning both a BM (bachelor of music) in the School of Music and a BA or BS in the College of Arts & Sciences, for example, and a double degree like that usually takes 5 years. Science degrees and music degrees are both time consuming majors with lots of requirements. Some music schools welcome double degree students, others strongly discourage it. There is also a B.A. in music (generally more of an academic music degree vs. a performance degree) that is usually easier to combine with another subject within the same school.
Read the essay linked above and see if it clarifies your goals. See which of the example students you identify with the most. Whether the essay helps or not, consider posting any questions to the Music Major forum. Applying to and auditioning at music schools is a different and more complicated process, and the parents and students in that forum are happy to help.
Some people who aren’t sure exactly what they want to do (or who want to keep all their options open) apply to some music schools for a BM program and go through the audition process, but also apply to schools that do not offer a performance-based music degree but where they could combine some sort of music study, lessons and ensemble work with a different major.