Lee You are quite correct. People who work in the U.S. Public School system are required by law/employment rules to report ANY suspected child abuse.
I am a parent who lives in the USA, and from YOUR DESCRIPTIONS... I am sorry to say this does sound like it is abuse (as generally accepted by society in the USA) if they are truly forcing you to wear a chastity device.
You have several options, find a trusted ADULT friend (over 30 years old - who does not work for a school, hospital, and a few other REQUIRED to REPORT abuse professions.) and get some sound ADULT wisdom. If you can't find someone, you may have to find some school counselor or friend and try to achieve some "deal" not to report (do so BEFORE you tell everything); however, legally that puts the counselor is a bad legal spot.
You need FIRST HAND ADULT advice and not the advice of strangers (including me) around the world who have no clue what your personal needs really are.
Now on a parental note: Parents MUST take steps to get a rebellious child into line. This does include taking way bank cards, cell phones and even the Internet (that was one of my favorites). I do NOT know what you did to make your parent decide to get you a chastity belt. (I can only assume the proposed punishment fits the crime. Therefore there may be other people you need to help be responsible to. You may need to man up.)
I suspect there is a lot on your plate now.
GOOD LUCK, get some ADULT advice and then come back here and tell us what happened.