Is getting into a top-tier medical school realistic for me?

You are asking if you should worry (on purpose?). Worrying is not helpful Your goal is ALWAYS the same at college, no matter where you are heading, to the medical school, engineering firm, any other place. Your goal is to have an A in every class, because of why not. Pretty simple, no reason to make it complicated. You have to take care of other things in your life. You have to take care of yourself, make sure that you are as much relaxed as possible, knowing what relaxes you is very helpful. You have to grow personally, broaden your horizons, meet interesting people, whatever else is really up to you. I would not include “worrying” in this list. Having a good plan for achieving in various aspects of your life is more helpful than worrying.