Nice work on a very strong preparation for any college. Clearly you have leaned heavily into Math / Comp-Sci. Using the statistics available from the College Board, about 100,000 students take the Calculus BC exam every year with only about 40,000 earning a 5. The fact that you took Calculus BC “early” and went on to take MVC and Linear at GT also shows strength in math, so it would be a priority to maintain your track record of academic excellence in those as well as your other courses.
Your math acceleration is a strong preparation for engineering or CS. It is a preparation shared and acceleration shared by a large percentage (perhaps about a third) of successful applicants to math-related majors at T20 schools. So in isolation, this is a stepping stone to success in College but may not be a significant admissions advantage.
Your EC’s and awards show nice breadth and some depth, particularly in Clarinet. If you are an especially strong clarinetist, submitting a studio recording is something you could consider to share your talents. For an T20 application, you might describe aspects of your business that were impactful in your community or showed personal leadership as those are aspects of the information that you provided that may be viewed as less clear.
A lot is made on this website about being assessed in the context of your high school, especially academically. You self-studied Calc BC to enable you to take MVC and LA. In my view, that shows both talent, initiative and hard work. Even if others disagree on this point, it is hopefully less controversial that you will be directly compared with students from your HS especially in your year. You will also be compared with students elsewhere with interests in CS and engineering. Top 5% in a class of 400 is a general rank of 1-20. Though your school does not rank, your likelihood of admission likely does depend somewhat on the strength of other students and “2” would be different from “19” academically, and in terms of EC’s.
The most important factor is likely your school’s track record for admission and matriculation for top 5% students. Even in the same county, some public schools might place 25% of their student body in USNWR top 20 schools while others might place 5%. Your school may have this information, or you may be able to approximate an estimate through the school’s published profile.
As with any student with strong academics and EC’s, it is exceedingly difficult to stand out against other students nationwide. If T20 is a possible goal, something you can do now is to look over the supplemental essays from each of the schools that fit your interests and start thinking about answers that would fit your life’s narrative.