My menu can't hold all my categories?

That’s likely a server limitation –

https://www.wpbeginner.com/wp-tutorials/how-to-fix-the-custom-menu-items-limit-in-wordpress/

Thank you for the help WPyogi! My serverholders did not let me change in the php.ini-file but they helpt me anyway. So my solution to this was to add:
php_value max_input_vars 3000 ,
into the .htaccess-file. Now it works perfekt! Thanks for the help. I use loopia.se as serverhosts.

Excellent, glad to hear it :)!