USC and Vanderbilt admit students to their universities in general, not on the basis of your major. At Cornell, you simply have to choose a college to apply to; you can get a BA in computer science from the College of Arts & Sciences (there’s a BS in CS offered in the school of engineering, but if you’re really concerned you can just take all the same classes they do).
GEorgia Tech doesn’t specify whether or not you have to apply to a specific major or college - you used to have to, but I think they removed that requirement. In either case, your SAT math score puts you in the middle 50% of accepted students, so you’re fine. (You’re also in the middle 50% at Cornell and USC.)
To put this in perspective, your SAT math score puts you in the top 10% of all test takers in the U.S.
Since you are low-income and need a lot of financial aid or merit aid to attend college, you need to add some matches and safeties to your list anyway. As an African American female interested in computer science and with test scores as high as yours, you have a lot of options. First of all, don’t pass over your state’s public universities - you have some good ones. UF and Florida State are obvious choices, but there’s also New College of Florida if you are interested in a small college. And you’d easily be eligible for a full-ride from Florida A&M.
Secondly, if you look at private (and some public) schools even just a tier down from where you’re currently looking you’d be competitive for some big merit aid awards. At University of Alabama you are eligible for their Presidential Scholarship (which is automatic, and full-tuition) and can compete for their Academic Elite scholarships (which are full rides). You’re eligible for the Ramsey Foundation Fellows scholarships at UGA as well. There’s the Banneker/Key Scholars program at the University of Maryland (which has an excellent CS department). At American University, you could be eligible for a full scholarship through the Frederick Douglass scholars program. Duke and Emory (which I’d say are at least on par with USC and Vanderbilt) both have full scholarship programs that you are potentially competitive for.
Basically, look for colleges at which you might rank in the top 15-25% of applicants and that offer large merit scholarships. Small liberal arts colleges (think Amherst, Pomona, Williams, Swarthmore, Pitzer, Claremont McKenna, Haverford, Davidson, Grinnell, Macalester, Bates, Carleton, Colby, Kenyon, Wooster…the list goes on) are good for this, too, because they tend to have fewer applicants and thus higher admissions rates. (Women’s colleges - like Scripps, Smith, Bryn Mawr, Mount Holyoke, Wellesley - can be great for this! For example, if you went to Scripps you could major in computer science at Harvey Mudd.) However, a lot of the elite LACs have generous merit aid policies, and many meet 100% of your financial need.
The short version is that your scores are still competitive with most top schools, but you should mix it up a little bit because of your need for money.