I'm currently in nursing school and know I don't want to do L&D or anything with babies. (At least that's what I feel now, but I am keeping an open mind). There are many facets to nursing and to each their own, if you have found yours then go for it! If you approach your mentor with your desire perhaps there is a way for you to get what you want and they have not wasted their time and money training someone that will jump ship because they are unhappy.
Good luck in whatever you choose!