Take things one thing at a time, there will be lots of time for those decisions after you complete nursing school. Maybe you won't even want to be a nurse at all! Not everyone that begins nursing school in the first place concludes that nursing is really their calling.
Also, when you are in school, you will attend lots of different rotations, through many specialties- perhaps another specialty will call to you.
I don't think (flame me, if you wish,) that school nursing is a wise place for a new grad, anyway. It takes a lot of experience, IMO, to be able to look at all the facets of the problems that come up in this area of nursing. Many of your cares will be social, not medical. I had nearly 30 years fulltime experience before I entered school nursing, and not a day goes by where something I have not seen before occurs! It is not as predictable and routine as many people outside this specialty think.