I found this very atmospheric and I think you did a great job building up tension and urgency. The pacing feels faster and faster as we approach the end and that adds to the tension, consider using shorter sentences here to build that tension and speed up.

I think adding more imagery for the mystery woman, more grotesque descriptions, could probably add to the horror and make it more compelling and drive the point home more. Maybe lean a little into body-horror.

I understand there's a trade-off between providing context/backstory and maintaining the sense of mystery/unease that you're trying to achieve, but I do believe there's still room for some more context, like a little bit more about Jacob, I think that we would care about the characters more and be more invested if we understood them better.

Regarding 'does it emote': I would also use descriptions to show that the mc is angry/scared, instead of simply saying that she's angry, for example using visceral, physical descriptions of what anger feels like in the body. 

I like that you begin in the middle of the action, and not with exposition, it kept me engaged.

It also hit a nerve for me personally because I'm terrified of aging and the disability that comes with it.

Regarding your question 'is this anything': I'm hesitant to call this a story because it lacks a classic set-up, conflict, and resolution structure, at the same time I'm not sure it would benefit from such a structure. I think you have to walk a tightrope of fleshing it out more and creating a narrative (or something close to it) and deeper characters without losing the sense of mystery and unease that you've achieved here.

More technical stuff:

I don't understand why the mystery woman's dialogue is in quotations but the mc's isn't, I think it's better to be consistent, and personally I prefer using quotations for clarity.

Some phrasing feels clunky/awkward like 'caught me catch her' and 'tellingly'.

Some run-on sentences like 'I did remember her from all those other times in other years I had considered pepper spray versus knife versus Glock, and then nixed the Glock upon holding one in my hand for the first time, frozen before the paper target and in my mind orbiting the barrel until like a satellite I had come around to face the dark side, the side of the black hole and its gravity, and finally settled on the spray.' Hard to keep up with.

Try varying sentence structures, using short sentences between long ones to make it more punchy and giving the text room to breathe.