I think that this was a solid story with good imagery, especially the description of the creatures as "gummy," it brought to my mind the gumheaded monsters from Silent Hill 4. It was also well done in terms of it being a simple story, presenting a common childhood scenario that most people can put themselves in, but distorting it towards something terrible that you never directly address. These are great qualities, and I think they make it an overall good read. That being said, I do think there are a few things you might want to keep in mind when you write something like this again: 1) The voice of the narrator seemed to be that of a young girl, yet it was not totally consistent, and I think you could have shorn that up by using more interesting adjectives than "closet-like;" 2) It would have been a bit more interesting (to me) if the set-up of the story and the girl doing gymnastics tied more into the terror, perhaps having it so that she broke one of the jars and not a plate, though that would probably make a longer story; 3) It may have made the story more compelling if you gave the mother more details to establish her character, such as making her more overbearing or kind so that it invites the reader to imagine how all the elements within connect.
Once again, it's a strong story, and I'm glad I read it. The suggestions I have made are just what I would have done if I were writing a similar story, so I totally understand if they do not align with your overall conception of it.