I liked your story but I think it is a bit wrong to say that this relatively thin skewer is preventing her from bending her body.
It should be relatively flexible

Womb skewering is nice idea too, but maybe dont stop there and do play piercing with her internal organs too.

she could make small incisions in her skin to get access to her ovaries pull them out and then pierce them

also instead of going to the bathroom she can piece her balder and let pee out like a man.

If you think about more moderate version then probably you could continue story on how she removes those skewers while Sai is away
and experiments with them herself.