Relax. Most kids you age are going though similar things. Most kids are worried, scare, anxious, and excited about going off to college. It is a big change. The thing you have to realize is that you are barely at the beginning of your adult life and that nothing is set in stone. If you decide that nursing isn't your thing, you can change your major. If you want to try clubs or intramural sports, feel free. If a decade from now you want to change careers, you can.
There are millions of people who have changed majors, changed jobs, changed careers, taken up new things in their 30s, 40 and on into their 70's and 80s.