I have to mount the blog posts manually, but I\'m not sure if this is the correct way to work, It only brings 9 pages, with 4 posts each, but the blog has 83 posts!
The below note is from this codex section.
Note: With use of the offset, the above query should be used only on a category that has more than one post in it, otherwise there'll be no output.
So in-order to display all posts, there should be at-least 2 posts in each categories.
You can try Loops to get all posts. Check The Loop in Action also.
Problem is your 'numberposts' is set to 4 Put it at -1 to get all posts:
'numberposts' => -1,
If you don't set numberposts here, WordPress will pull the number of posts from your Dashboard settings (under Settings -> Reading)