HaBO: Erotica Written in Second Person

This HaBO comes from A., who wants to find this interesting erotic romance book:

I saw a post online looking for a book that looks awesome. The site also recommended emailing you, so I am in hopes that you may know what it is!

I’m looking for an erotic book written in second person, where ‘you’ are a woman being trained for BDSM by ‘your lover’, and are exposed to increasingly varied experiences till finally ‘you’ end up being the madame of the house. It’s written in a very elegant way. Themes include multiple partners, public humiliation, etc.

I read it maybe 15 years ago but have no idea when it was written.

There’s an encounter with a swim teacher or PE teacher, where the teacher asks if the protagonist is wearing a menstrual pad; protagonist says no and teacher asks her to show her.

She goes to a girls training school or something; a woman makes all the girls come outside one at a time, nude, and hoses them off with a water hose; when it’s the protagonist‘s turn, she is brought to orgasm by the stream of water.

Look, all kinds of things can be published, though this seems like it’d be on more of a writing site like something similar to Wattpad, given the “reader insert” theme of the book.