You already have some terrific college options!
IIRC, both oncology and gastroenterology are fellowships done after your residency…so you are way ahead of yourself on those @WayOutWestMom will tell me if I’m right.
Regardless….your goal now should be to do your very best in undergrad. Put medical school and specialties out of your head…other than to take the required courses for medical school applicants.