Three levels category menu

Hi everyone,

I am totally lost…
I am trying to build a three levels menu based on categories.
The problem is that it has to be built in a way that the owner of the site will be able to add categories and custom post types on the frontend without going to the appearance -> menus section.
I use wp_list_categories to display the parent categories. Then, I am using get_the_category to to display categories list outside the loop. Last level, I use get_posts to retrieve posts info.
Firstly, it doesn’t work. I only get parent categories and posts.
Secondly, this scheme won’t allow me to add a css class to active items and so give the frontend user the ability to know where he is.
Does anyone has an idea of how to build such a menu system in WordPress?
Thanks!

Here is my code :

<div class="navigation col-lg-4 col-md-4 col-xs-4">

		<div class="col-lg-4 col-md-4 col-xs-12">

			<?php
			    $args = array(
				'show_option_all'    => '',
				'orderby'            => 'name',
				'order'              => 'ASC',
				'style'              => 'none',
				'show_count'         => 0,
				'hide_empty'         => 0,
				'use_desc_for_title' => 1,
				'child_of'           => 0,
				'feed'               => '',
				'feed_type'          => '',
				'feed_image'         => '',
				'exclude'            => 1,
				'exclude_tree'       => '',
				'include'            => '',
				'hierarchical'       => 1,
				'title_li'           => __( 'Categories' ),
				'show_option_none'   => __( 'No categories' ),
				'number'             => null,
				'echo'               => 1,
				'depth'              => 1,
				'current_category'   => 0,
				'pad_counts'         => 0,
				'taxonomy'           => 'category',
				'walker'             => null
			    );
			    wp_list_categories( $args );
			?>
		</div>

		<div class="col-lg-4 col-md-4 col-xs-12">

				<?php

		$categories = get_the_category();

			if ($categories) {

				$category_id = $categories[0]->cat_ID;

			} else {

				$all_cats = get_categories();

				foreach ($all_cats as $value) {

					if(is_category( $value->slug )) {
						$category_id = $value->cat_ID;

					}
				}
		}

		if (isset($category_id)): 

			$category_id = get_the_category();
			$separator = ' ';
			$output = '';
			foreach ($category_id as $category_link) {
				$output .= '<a href="'.get_category_link( $category_link->term_id ).'" title="' . esc_attr( sprintf( __( "View all posts in %s" ), $category_link->name ) ) . '">'.$category->cat_name.'</a>'.$separator;
			}
			echo trim($output, $separator);

			    $videos = array(
				'posts_per_page' => 99,
				'post_type' => 'video',
				'orderby' => 'menu_order',
				'order' => 'DESC'
			);

			$cat_posts = get_posts( $videos );

				foreach ( $cat_posts as $post ) : setup_postdata( $post ); 

			?>
						<li><a href="<?php the_permalink(); ?>">
						<?php the_title(); ?>
						</a>
						</li>	

			<?php endforeach; wp_reset_postdata();
			endif;
			?>

		</div>

		<div class="col-lg-4 col-md-4 col-xs-12">
		</div>

	</div>