How to display dynamic content in start_lvl function

I am creating a custom nav walker but having trouble outputting parent menu item title in start_lvl function. I want to output it right after the div class="dropdown" in the following start_lvl function.

function start_lvl($output, $depth = 0, $args = array()) {

        $indent = str_repeat("\t", $depth);

        if ($depth == 0) {

            $out_div = ' div class="dropdown-wrapper"div class="dropdown"This is where I want to output parent item title';
        }
        else {
            $out_div = '';
        }
        // build html
        $output.= "\n" . $indent . $out_div . 'ul' . "\n";
    }

Here is the complete nav walker code.

class my_custom_navwalker extends Walker_Nav_Menu {

    function display_element($element, $children_elements, $max_depth, $depth = 0, $args, $output)
    {
        $id_field = $this-db_fields['id'];
        if (is_object($args[0])) {
            $args[0]-has_children = !empty($children_elements[$element-$id_field]);
        }
        return parent::display_element($element, $children_elements, $max_depth, $depth, $args, $output);
    }

    function start_lvl($output, $depth = 0, $args = array()) {

        $indent = str_repeat("\t", $depth);

        if ($depth == 0) {

            $out_div = ' div class="dropdown-wrapper"div class="dropdown"';
        }
        else {
            $out_div = '';
        }
        // build html
        $output.= "\n" . $indent . $out_div . 'ul' . "\n";
    }

    function start_el($output, $item, $depth = 0, $args = array() , $id = 0) {
        global $wp_query;

        $indent = ($depth) ? str_repeat("\t", $depth) : '';

        $class_names = $value = '';
        $classes = empty($item-classes) ? array() : (array)$item-classes;
        $class_names = join(' ', apply_filters('nav_menu_css_class', array_filter($classes) , $item));
        // $class_names = ' class="'. esc_attr( $class_names ) . '"';

        if ($args-has_children  $depth == 0) {
            $has_sub = ' has-sub';
        }

        $output.= $indent . 'li id="menu-item-' . $item-ID . '"' . $value . 'class="' . $class_names . $has_sub . '"';

        $attributes = !empty($item-attr_title) ? ' title="' . esc_attr($item-attr_title) . '"' : '';
        $attributes.= !empty($item-target) ? ' target="' . esc_attr($item-target) . '"' : '';
        $attributes.= !empty($item-xfn) ? ' rel="' . esc_attr($item-xfn) . '"' : '';
        $attributes.= !empty($item-url) ? ' href="' . esc_attr($item-url) . '"' : '';
        $prepend = '';
        $append = '';

        //$description = !empty($item-description) ? 'div class=""' . $item-description . '/div' : '';
        // if($depth != 0)
        // {
        //         $description = $append = $prepend = "";
        // }


        $item_output = $args-before;

        $item_output.= 'a' . $attributes . '';

        $item_output.= $args-link_before . $prepend . apply_filters('the_title', $item-title, $item-ID) . $append;
        $item_output.= '/a';
        //$item_output.= $description . $args-link_after;
        $item_output.= $args-after;
        $output.= apply_filters('walker_nav_menu_start_el', $item_output, $item, $depth, $args, $id);
    }

    function end_lvl($output, $depth = 0, $args = array())
    {
        $indent = str_repeat("\t", $depth);
        if ($depth == 0) {
            $out_div_close = '/div/div';
        }
        else {
            $out_div_close = '';
        }
        $output.= "$indent" . "\n";

        $output.= "/ul" . $out_div_close . "\n";
    }
}

Any help would be highly appreciated.

thanks in advance.