There is still a big difference between animation design and costume design, but animation design needs the elements of costume design. If your experience permits, I suggest you minor in fashion design. If you are more interested in fashion design than animation design in your junior year, you can change your major when applying for graduate school, because it is easier to minor in it. If the family conditions are ok, you can go to Britain to study for a master's degree in fashion design, which only takes 1 year.