Generally, the chances for any OOS applicant to UNC-CH are somewhat problematic due to the highly competitive nature of OOS applications there: UNC-CH admits OOS applicants in numbers that are calculated not to exceed 18% of an entering freshman class. See “Undergraduate Admissions” on Page 2, here: http://www.admissions.unc.edu/files/2013/09/Admissions__Policy.pdf. As a further example of the difficulty for OOS students to be admitted to UNC-CH, the entering Class of 2021 had a 14% acceptance rate for OOS applicants: http://admissions.unc.edu/apply/class-profile-2/.
If you look at the UNC-CH Common Data Set, here, https://oira.unc.edu/files/2017/07/cds_2016_2017_20170411.pdf, under Part C7 it states that standardized test scores, application essay(s), letter(s) of recommendation, and the rigor of your high school record are “very important” academic factors considered for freshman admission, whereas GPA and class rank are “important” academic factors considered for freshman admission. Extracurricular activities, talent, and character/personal qualities are considered as “very important” non-academic factors.
By way of comparison, our OOS high school usually has 8-10 students who apply, and 1-2 students who are admitted, each year to UNC-CH; and, with the exception of legacy students, our admitted students have SAT scores of 1500+, ACT scores of 33+, and weighted GPAs of 4.4+. These successful applicants also were involved in extracurricular activities that showed commitment over time (no “drive-by” ECs), and demonstrated leadership in the school as well as their ECs. Other kids in our city who I know were admitted to UNC-CH recently also had similar academic statistics and non-academic characteristics; and all of these kids were “unhooked” in admissions parlance (i.e., not a recruited D-1 athlete, or a URM, first-generation college student, etc.).
I concur with @Pastpower in that you really shouldn’t worry about subject matter tests for UNC-CH. You need to focus on those things that UNC-CH considers to be “very important” admissions factors and which are still within your control at this point – SAT/ACT test scores, LORs, and essays. I also think that you should try to get your SAT score up to a 1500; if you haven’t taken the ACT, you may wish to consider it; most students do better on one test over the other (my kids did much better on the ACT than the SAT, for example), and taking a test preparation course or two may help also. If you are applying EA, then you will have a foreshortened time frame in which to get your test scores up.
I don’t know whether your high school has Naviance or any similar program that gives information about how students at your high school have done in applying to colleges and universities; if so, you might peruse that data. Also, since your high schooI typically has a number of students who apply each year to UNC-CH, I would also try to meet with a guidance counselor at your school early in the Fall semester of your senior year (assuming that it’s too late now to do so this semester) to discuss application strategies for UNC-CH. If any former students from your school have been admitted to UNC-CH recently, the guidance counselor should be able to give some insight into how and why such student(s) were successful.
Since you have a leadership award from W&M, should we presume that you live in Virginia? If so, have you considered UVA and/or W&M? As an in-state applicant I think you would have a pretty good shot at either of those schools.