Immunity to Hepatitis A?

I am a 23 year old female interested in getting Hepatitis A vaccinations due to a location change and start of medical school. I recently had a blood titer done in order to verify my immunity status concerning Hepatitis A. I have never had any vaccinations or exposure to the virus (as far as I know). My test was for Hepatitis A antibodies and the result was nonreactive. My doctor told me this means that I am immune to Hepatitis A and therefore I do not need the vaccination series. How is this possible considering that I have never had any way to develop the immunity? Also, does the test result "nonreactive" really mean that I am immune? Thank you.

[nunuking]

My bother was tested hep A positive. His test result showed he has immunity. He was  living with my wife and I for 6 months. My wife was pregnant at that time and now she has given birth. We have been tested after knowing my  bother's scary result. We are both positive and have immunity. We scared our baby will catch it from us, and what does it mean having immunity? Why does'nt docter just say we have hep A. We are so scared about this virus, It feels like we are walking time bombs ready to get sick.