No matter how rigorous your high school is, there will always be limitations to what courses you can take. Maybe your school doesn’t offer AP Calculus. Maybe they do offer it, but you weren’t able to get into the class. Maybe it conflicts with another course that you need to take to graduate. The good news is that your school and its course offerings don't get to decide how intellectual you are.
Whatever interests you, you can almost certainly find a way to dive in and learn more about it. Take a course at a local community college. Take a free online class at Berkeley, Stanford or MIT. Watch videos at the Khan Academy. Do outside reading, start an independent study, or enroll in a community education course.
Don’t say things like, "I love math and want to major in engineering, but I couldn't take calculus because my high school didn't offer it." Intellectuals always find a way to learn.