When you said that The Origin only has 11 volumes, but it is

[Vertical Inc]

When you said that The Origin only has 11 volumes, but it isn't the end of the story, what did you mean by that? Can you elaborate for a Gundam newbie like me? Does that mean that there should be a 12th volume to finish the story, but they ended it prematurely?

Yeah this is a bit confusing…
Okay so there are 23 volumes of the paperback available. And the series ends at and is concluded properly at 23. But the 11 volumes of the hardcover only cover the first 22.
So here is the rub…Kadokawa have not published a hardcover for the contents of volume 23. And they only acknowledge that there are/will be 11 hardcovers.
Now that might change. They might have been acting coy and have plans to add the side-stories to a future volume 12 all along. But right now, we at Vertical are in the dark. We are literally planning on adding volume 23 to hardcover 11.
…even reading that explanation is confusing.