I'm terrible with names sadly. There are two scenes I remember though. One where the MC is waxed because her pubic hair grew in too much and another where the MC's mother's car had a sort of restraint system in the the back that she is put in and has some sort of figging like punishment after misbehaving in a store. The general vibe is that the mc is physically regressed but mentally aware of the situation. There may have been a little bit of a romance element if im not conflating stories, where the mc and another character share a diaper. I'll admit it was painfully niece, very punishment/pain focused in sections.
I'm looking for a story that I am fairly certain is around 10 years old (I think I read it in college) and is named something like "Be careful what you wish for" about a genie granting a woman the wish that people are treated like babies well into adulthood. It is fairly hardcore and I don't remember where I read it. It's been hard to search for because so many stories have that name across multiple sites and I get too many results.
I'm a little late this year, but it's that time of year for the Harry Potter series. Saturday night was #1, last night was #2, and tonight is #3.
I was just thinking of that one yesterday!