Pre-Med psycho...
please please relax. First off, be excited about going to college. Aside from the academic world, you are entering an intense phase of "growing up", meeting people, traveling (studying abroad was THE BEST thing I ever did) and just exploring all there is in this world.
Be open and receptive to different things; I ended up loving a lot of my general education classes more than my bio classes. And to be honest, in retrospect I wish I had majored in art & design or art history instead of biology. I still want to be a doctor, but i wish i had studied something other than bio.
Don't be in such a rush to go to medical school; I only decided to apply for medical school after I returned from England at the end of my junior year. It was a pain in the butt getting my med school apps/MCAT/recs in on time, but in the end I got into a school that I'm so excited about attending this fall. It all worked out really well.
Be aware to the basic things you need to do to get in to med school (required classes, recs, MCAT, research and clinical experience) but PLEASE don't neglect the wonderful, diverse experiences college has to offer. It may change the area of medicine you are interested in, and/or it may change your entire career path.