I’m just a junior in hs but I’m sure of what I want to major in. Can y’all give me insight? I’ve wanred to be a doctor or a marine biologist since I was a child, and all of my high school credits are heavily math and science based. But not too I realized I was passionate about political science & Psychology, so what major & minors would be the best for me?
You could always double major or major and minor. It really comes down to what you are interested in pursuing and what you could see yourself doing as a career. 
You could major in political science or psychology and be pre-med. Psychology is a very common pre-med major.
If you wanted to be a marine biologist, biology is your best major to help you prep for the graduate degree, but you could double major or minor or take some classes.