Wow, hey there anon!
Fellow 17-year-old girl here with victim POV rape and torture fantasies - I feel like in my case, though, while some of my depraved fantasies are rooted in self hatred/abuse, a significant portion of it stems from daddy issues/growing up in a broken home/all the cliche dark backstory bullshit.
While I fantasise about being brutally raped and tortured by strangers, my fantasies often have a theme around being kidnapped and "kept" by strange older men (indicator one) and "loved" in some weird abusive way (indicator two - inb4 playing armchair psychologist with myself, I have no experience with real father figure love etc so that must be how it's supposed to work, at least in the idea of some weird subconscious part of my head?). There's also a big aspect of psychological torture or manipulation in both my violent fantasies and my less violent ones.

But, yeah, the whole physical torture and abuse thing I fantasise a lot about (despite low physical pain tolerance/threshold and dislike of physical pain!) is definitely, at least in part due to a self hatred thing.

I feel like there's a bit of difference between my fantasies that are primarily driven by self hatred, and the ones that are driven by some sad urge to be "loved" and "wanted", though.