Yeah, it’s pretty cool that you’re keeping the Metroid motifs in mind when writing this. It makes the story not just smut. Authors should always keep in mind the impressions and compositions of the original source material - I feel as though a lot of writers miss out on that.
For some constructive feedback: I feel as though the strongest part of your story so far was been the cavern arc. I’m not 100% sure as to why, but I think it’s where I most believe that it’s Samus. She was physically inferior (as in most of the games), but ingenuity saw her though it. It was this part that made me actively root for her. The arc was short, but the payoff was great! I can sense the same sort of tension building now that we’re towards the end of the story, and am hoping for the same sort of sense of victory,
I’d also like to humbly ask that you don’t make the ending abrupt. I think that it’s a real shame how many authors, published or otherwise, don’t quite seem to deal with ‘the return’. That is: the hero has won, but we, the readers, need to be able to see the results of the success. We need to see the effects on the hero, their world, and if appropriate, the villains. To put it succinctly, it’s not just about the journey, but also the destination.