Not feasibly, I think. Her age and the ages of her siblings -- and therefore everyone's approximate birth years and the wedding date of her parents -- were already established in the first story, so to age her up I'd have to move this story a year or two or three later, and I've already set it questionably late as it is. Given a choice between "I know I said she was thirteen and acted like it, but let's pretend she was sixteen the entire time!" and "Okay, the key development requires her to have a more accurate memory than is probably realistic for age 3.5, but please roll with it" ... I'm inclined to go with the latter.

I have toned down a few things, and I was more vague about details than I thought I was in the first place (which helps), and I'll take another pass later. Ultimately I'm leaning towards just going with it; the theme of this project is basically "better to post with recognized flaws than never post at all".