Trying to create plugin for results per page – Woocommerce

Hey all, I need some help here if anyone is able to chime in and offer their support. So I want to create a plugin that will offer a dropdown on the catalog page of Woocommerce so that users can select how many products are being viewed per page. I almost (in my eyes) have it but cant quite work out the kinks. Any takers?

Here is what I have:

function woocommerce_sortby_page() {

	if ('woocommerce_catalog_page_ordering'==$twelve)
  {
  add_filter('loop_shop_per_page', create_function('$cols', 'return 12;'));
  }
elseif ('woocommerce_catalog_page_ordering'==$sixteen)
  {
  add_filter('loop_shop_per_page', create_function('$cols', 'return 16;'));
  }
  elseif ('woocommerce_catalog_page_ordering'==$twenty)
  {
  add_filter('loop_shop_per_page', create_function('$cols', 'return 20;'));
  }
  elseif ('woocommerce_catalog_page_ordering'==$twentyfour)
  {
  add_filter('loop_shop_per_page', create_function('$cols', 'return 24;'));
  }
  elseif ('woocommerce_catalog_page_ordering'==$twentyeight)
  {
  add_filter('loop_shop_per_page', create_function('$cols', 'return 28;'));
  }
else
  {
  add_filter('loop_shop_per_page', create_function('$cols', 'return 4;'));;
  }
}

function woocommerce_catalog_page_ordering() {
?>
<form action="<?php woocommerce_sortby_page ?>">
<select name="woocommerce-sort-by-columns">
<option value="<?php $twelve ?>">12</option>
<option value="<?php $sixteen ?>">16</option>
<option value="<?php $twenty ?>" selected>20</option>
<option value="<?php $twentyfour ?>">24</option>
<option value="<?php $twentyeight ?>">28</option>
</select>
</form>
<?php
}

add_action( 'woocommerce_pagination', 'woocommerce_catalog_page_ordering', 20 );

I’m sure I am probably way off but am new to plugins and relatively new to the codex and PHP..

Here is how Woo does their “Show results per page” which I assume would be similar to what I need to do?

<form class="woocommerce_ordering" method="POST">
	<select name="sort" class="orderby">
		<?php
			$catalog_orderby = apply_filters('woocommerce_catalog_orderby', array(
				'menu_order' 	=> __('Default sorting', 'woocommerce'),
				'title' 		=> __('Sort alphabetically', 'woocommerce'),
				'date' 			=> __('Sort by most recent', 'woocommerce'),
				'price' 		=> __('Sort by price', 'woocommerce')
			));

			foreach ( $catalog_orderby as $id => $name )
				echo '<option value="' . $id . '" ' . selected( $_SESSION['orderby'], $id, false ) . '>' . $name . '</option>';
		?>
	</select>
</form>

Thanks for the help and Happy Holidays!