It sounds like a really difficult issue, Janeshuff. However well done on you for listening to your reader feedback.
I think as others have suggested, a close psychic distance is your answer. The character’s subjective thoughts, feelings, and reactions can never be gratuitous. These will also advance your plot, by contributing to your character’s arc.
I agree that trying to give a blow by blow (sorry for the pun) of the “practical” details of the scene could easily feel like overkill.
I really like Jonathan’s idea of having the character describe / notice seemingly irrelevant details during her ordeal. The mind can go to strange places at times of extreme trauma, and this can be a powerful (yet “tasteful”) way of communicating the severity and horror of what is going on. In other words you can communicate how extreme the violence is by showing how distorted, fragmented or dissociated her perceptions and thoughts become.
Even if they might seem out of context, it might be worth posting one of your extracts here so that we can have the specific example of what you are struggling with.
However you decide to work it out, best of luck with it.