Choose a major that you are interested in and passionate about. You can get into med school with any major. That being said, you will still need to do well in your science courses that are prerequisites for medical school. The obvious choice for major is psychology but don't choose this if it's not your interest. At this point in time you may think you want to be a child psychiatrist but as you are exposed to more areas of medicine you may find that you may be more interested in another field.