Your "surface" antibody titer (which is what the school is looking, anti-HB-s) CAN be positive even after being infectef if you enter "natural immunity" stable condition. It also can be negative if your infection is chronic but somewhat active. Other serologic tests will be needed to determine activity level:
Understanding Hepatitis B Serology | Hepatitis Central
Also, google "cdc hepatitis b interpretation" It will show a nice pdf table which you better save because you will be expected to recite and explain it by heart at any moment. In pretty much any NP specialty, it is daily bread and butter.
Again, your school WILL NOT can you out for being infected, it is pretty much 100%. They don't do it for things which are potentially much more transmissible, like positive Tb test. Ask your health care provider for doctor's note explaining your status and come speak with your clinical coordinator. Ask them to speak with CastleBranch if your school uses this d***ed organization, because otherwise you will spend long hours chatting with their staff, most of whom have no idea whatsoever of what they are paid their muneys for (from my experience, with all Tb tests being positive for life). That will be that.
P.S. I thought that interpretation of hep B serology was NCLEX material. We were drilled at it till death as undergrads, and at least in my current NP program it surfaces on exams under premice of "you guys must know it by heart already".