Since you asked for feedback: Part one of the sandra story is very decent but would be better if you trim the useless bits (wink). remember: show, don't tell! you dump a lot of exposition up front. you thought things through. that's good! but a big chunk of the story could have been shown with action or dialogue or just cut out. for example when the narrator is about to rape her you keep hammering home how powerless she is. that's obvious! compare it to the "think she's trying to swat my hand away out of reflex" line. it shows action, her psychological state, how she doesnt want to be touched, how the amputation is still new to her. way more effective! also the narrator feels a bit flat. he's never surprised by anything, always knows what he's doing next and worst of all, constantly describes how aroused he is.

the second part is much stronger. things happen. we see how she lives every day, everyday moments. the narrator shows emotions. it's a compelling short story.

idk if you wrote emma daily life aswell but it's very good in those aspects. it's good that there is dialogue instead of exposition. the family members have distinct personalities. the mother seemed at first like she was secretly disappointed with emma's choice but then she got explicit too so maybe not? idk if that was on purpose but i would have found it interesting. like in those videos of people who transitioned where you can see the father looks dead inside. the part where the machine suddenly kicks on and starts aggressively milking her is great. you could have added how the mother cringed internally watching that. The line "But friends might complicate things—emotions and all" doesn't sound like something a real person would say.

Whatever, keep going, you're developing a unique style.