How can I get my pagination loop to display the correct number of total pages?

Question

Currently my pagination is showing 7 posts on the first page and 6 on each page after. This is what I want. The current readout looks like this:

.

The total count of my pages changes as soon as I navigation to another page (see below):

I checked my loop in my template and my function in my functions.php and could not figure out what the issue was. Could someone please help me figure this out?

TEMPLATE:

<?php get_header(); ?>
<section class="component" role="main">
<header class="header">
<h1 class="entry-title">Blog</h1>
</header>
<section class="component responsive">

<?php
$paged = ( get_query_var( 'paged' ) ) ? get_query_var( 'paged' ) : 1;



global $query_string;
parse_str( $query_string, $args );
if ($paged == 1){
    $args = array(
           'posts_per_page' => 7,
           'paged' => $paged
        );
    query_posts($args);
} else {
    $args = array(
           'posts_per_page' => 6,
           'paged' => $paged
        );
    query_posts($args); 
}

$custom_query = new WP_Query( $args );
$post_number = 0;


if ( have_posts() ) : while($custom_query->have_posts()) : $custom_query->the_post();

    $post_number++;

    if ($post_number === 1 && $paged === 1):

    if ( has_post_thumbnail()) {
    // do stuff if there is a post thumbnail
    ?>

            <div class="recent_articles_hero" style="background: url('<?php the_post_thumbnail_url(); ?>'); background-size: cover; background-position: 50%;">
                <div class="block_item_overlay"></div>
                <div class="recent_articles_content">
                    <h4 class="section_label"><?php echo get_the_date('F j, Y'); ?></h4>
                    <h1><?php the_title(); ?></h1>
                    <a href="<?php the_permalink(); ?>" class="button_styling">
                        Read More
                    </a>
                </div>
            </div>
        </section>

    <?php } else {
    // do stuff if there is not a post thumbnail
    ?>

            <div class="recent_articles_hero default_post_preview">
                <div class="block_item_overlay"></div>
                <div class="recent_articles_content">
                    <h4 class="section_label"><?php echo get_the_date('F j, Y'); ?></h4>
                    <h1><?php the_title(); ?></h1>
                    <a href="<?php the_permalink(); ?>" class="button_styling">
                        Read More
                    </a>
                </div>
            </div>
        </section>

    <?php } ?>

    <section id="articles_wrapper" class="block_items_container">
    <?php else: 

        if ( has_post_thumbnail()) {
        // do stuff if there is a post thumbnail
        ?>  

            <div class="block_item article" style="background: url('<?php the_post_thumbnail_url(); ?>'); background-size: cover; background-position: 50%;">
                <div class="block_item_overlay"></div>
                <h4 class="section_label"><?php echo get_the_date('F j, Y'); ?></h4>
                <div class="block_item_content">
                    <h3><?php the_title(); ?></h3>
                    <p><?php echo apply_filters( 'the_content', wp_trim_words( strip_tags( $post->post_content ), 12 ) ); ?></p>
                    <a href="<?php the_permalink(); ?>" class="button_styling">Read More</a>
                </div>
            </div>


        <?php } else {
        // do stuff if there is not a post thumbnail
        ?>

            <div class="block_item article default_post_preview">
                <div class="block_item_overlay"></div>
                <h4 class="section_label"><?php echo get_the_date('F j, Y');?></h4>
                <div class="block_item_content">
                    <h3><?php the_title(); ?></h3>
                    <p><?php echo apply_filters( 'the_content', wp_trim_words( strip_tags( $post->post_content ), 12 ) ); ?></p>
                    <a href="<?php the_permalink(); ?>" class="button_styling">Read More</a>
                </div>
            </div>

        <?php } ?>
        <?php endif; ?>

    <?php endwhile; else : ?>
<?php endif; ?>
    <div class="clear"></div>
    <?php if (function_exists("pagination")) {
        pagination($custom_query->max_num_pages);
    } ?>
    </section>
</section>

<?php get_template_part('subscription-section'); ?>

<?php if ( ! post_password_required() ) ?>

<?php get_footer(); ?>

FUNCTIONS.PHP:

// numbered pagination
function pagination($pages = '', $range = 4)
{  
     $showitems = ($range * 2)+1;  

     global $paged;
     if(empty($paged)) $paged = 1;

     if($pages == '')
     {
         global $wp_query;
         $pages = $wp_query->max_num_pages;
         if(!$pages)
         {
             $pages = 1;
        }
     }   

     if(1 != $pages)
     {
         echo "<div class=\"pagination\"><span>Page ".$paged." of ".$pages."</span>";
         if($paged > 2 && $paged > $range+1 && $showitems < $pages) echo "<a href='".get_pagenum_link(1)."'>&laquo; First</a>";
         if($paged > 1 && $showitems < $pages) echo "<a href='".get_pagenum_link($paged - 1)."'>&lsaquo; Previous</a>";

         for ($i=1; $i <= $pages; $i++)
         {
             if (1 != $pages &&( !($i >= $paged+$range+1 || $i <= $paged-$range-1) || $pages <= $showitems ))
             {
                 echo ($paged == $i)? "<span class=\"current\">".$i."</span>":"<a href='".get_pagenum_link($i)."' class=\"inactive\">".$i."</a>";
             }
     }

         if ($paged < $pages && $showitems < $pages) echo "<a href=\"".get_pagenum_link($paged + 1)."\">Next &rsaquo;</a>";  
         if ($paged < $pages-1 &&  $paged+$range-1 < $pages && $showitems < $pages) echo "<a href='".get_pagenum_link($pages)."'>Last &raquo;</a>";
         echo "</div>\n";
     }
}

Just to be clear, I am trying to get 7 posts to display on the first page and 6 posts on the rest.