Funny--you sound just like me! I also have a previous degree in Anthropology, and now I'm a PHN. I love it and if working with underserved people, especially immigrants, is your passion, public health is the place to be. I work with pregnant moms and babys, among many other things that I do. There's a nursing shortage in PH too.
During nursing school, you will have a "capstone" or leadership rotation, where you will basically work FT as a nurse. Request to be placed in a PH setting, and then you can get your foot in the door. This is what I did, and now I work there!
Most PH departments (local and state goverment operated - a downside d/t all the beauracracy) require a BSN, but if you have a previous BA they might accept that if you're going for a 2 year RN degree.
Look into your local health departments and at local "free"/community clinics. I found nursing school really focused onthe hospital setting, but if you know PH is where you want to be, don't lose sight of that. It's SO much better than the hospital!!
Check out the Nursing Reinvestment Act for scholarship
info if this is definitely your interest. Good luck!
Keep me posted.