my parents are really upset with my desire to change majors

Yes, add the pre med courses and finish the CS degree. Many students get no help from parents for med school. Once you get your undergrad degree, you are free to apply to med school. You might need a gap year because you might not be ready for the MCAT unless you’ve alresdy been taking the pre med classes. (You could earn $ for med school with the CS degree, too)