If your post is accurate, you have a naming error that will prevent additional larger images from showing up: there are no additional medium images as your filenames suggest, and a small additional image named pooh_01_MED.jpg would require pooh_01_MED_LRG.jpg to be seen as a large additional image.

That naming error wouldn't prevent the small additional images from showing, though.

Parts of the question that Ajeh didn't ask:
What directory are the small additional images loaded into on the server?
What directory are the large additional images loaded into on the server?

If the filenames start with pooh, they should all be seen as additional images if they are loaded into the same directory, and the large images into the /images/large/wp/ directory.