3 Detentions for writing stories on school drive

I am a 17 year old high school senior, and I have recently taken to writing short stories based off prompts from r/writing prompts. I wrote these on my school computer being that it is the only computer I have. I write as I think, so I did have characters cuss if I thought it fit the narrative, and I wrote about taboo subjects like sex and drugs.

The head of discipline at my school said what I wrote violated the technology user agreement I signed at the beginning of the year, but the agreement is very vague and he got me under “misconduct of a school device,” nothing specifically about google docs. I tried to explain to him that Shakespeare talked about rape, The Outsiders discusses sex and murder, and To Kill a Mockingbird talks about rape and racism; all of these books have been taught to us in English class. He gave me three detentions.

My English teacher agrees with me and is against censorship and whitewashing. What should I do?