It's awesome that you've made it this far. I've still got a year more myself before I graduate high school, and it's definitely a struggle for both me and students around me that don't even have mental illnesses.

People do not need to know your private business. If they ask, you are not required to tell them. Vague responses will be fine, if they push you are more than able to assert yourself and say that it is private for no reason other than that you prefer people to know you by your capabilities, not disabilities.