how can i add all my tags to tagcloud?

If you’ll take a look at wp_tag_cloud Codex page, then you’ll se a list of all args that function takes.

On that list you’ll see param called number that defines the maximal count of tags to show. It’s default value is 45.

Later you can read that:

number (integer) (optional) The number of actual tags to display in
the cloud. (Use ‘0’ to display all tags.) Default: 45

So this should do the trick:

<?php 
    $args = array(
        'taxonomy' => array( 'post_tag', 'category' ), 
        'number' => 0
    ); 

    wp_tag_cloud( $args );
?>