You really need to look at the schools and see if they care about your major…for example, The College of New Jerseiy requires that you state what major you want to be admitted into and it is difficult to change. But Case Western Reserve University has a “Single Door” admissions policy and you say what you are interested in but you can change your mind at any point and it is easy to switch majors (not including all the coursework you need to take!) but if you said you wanted CS and then decided on Biochem it wouldn’t matter.
I would get recommendations for CS from your math teacher or science teacher…I would not worry about being CS specific.