Advice for nursing school

I'm 17 and I'm going to be a senior in a couple of weeks. I have had a really hard time deciding what I want to do but the other day I thought about getting into nursing. I am thinking more along the lines of a children's nurse in like a doctor's office or just something that specializes in children. My grades were not the best in high school, C average but I'm going to try really hard to get them up this year. I know nursing school is really hard to get into. I was thinking about seeing if I can switch into our Health Occupations class next year and trying to become an lna when I turn 18. I'm also taking anatomy and physiology and I have taken sciences every year so far. Would be bad grades from before be an automatic no for nursing school or is it something I should go for? Does anybody have some advice?