Woocommerce Advanced Shipping – Custom Match Function with Custom Product Attributes

This is my first post here so I apologize if I do not do it correctly.

I am using Woocommerce Advanced Shipping plugin on a winery website to programmatically offer penny (0.01USD) shipping for orders with 6 or more bottles (as it is efficient to ship in multiples of 6). However, this client offers products that include 2 or 3 bottles. The quantity condition does not work for me because a three-bottle product counts as a single product when calculated for quantity.

I have begun trying to write a custom condition function as the guide here explains: http://docs.shopplugins.com/article/41-developer-adding-a-custom-condition

I feel like I am getting close, but it still does not work. Here is my code:

/**  Woocommerce Advanced Shipping (WAS)  **/

function check_total() {

    // Only run in the Cart or Checkout pages
    if ( is_cart() || is_checkout() ) {

        global $woocommerce, $product;

        $total_bottles = 0;

        //loop through all cart products
        foreach ( $woocommerce->cart->cart_contents as $product ) {

            // Add all bottles, 'bottles' is custom attribute set on the product page
            $total_bottles += $product['bottles'];

        }

    }
    return $total_bottles;
}


/**
 * Add condition to conditions list.
 *
 * @param       array   $conditions     List of existing conditions.
 * @return      aray                    List of modified conditions.
 */

function was_conditions_add_bottles( $conditions ) {

        // 'General', 'User Details', 'Cart' are default groups, you can also use something custom
            $conditions['General']['bottlenum'] = __( 'Bottles', 'woocommerce-advanced-shipping' );
    return $conditions;
}
add_filter( 'was_conditions', 'was_conditions_add_bottles', 10, 1 );


/**
 * Add value field for 'bottles' condition
 *
 * @param       array   $values         List of value field arguments
 * @param       string  $condition      Name of the condition.
 * @return      array   $values         List of modified value field arguments.
 */
function was_values_add_bottles( $values, $condition ) {
    switch ( $condition ) {
            case 'bottlenum':
                    $values['field'] = 'text';
                    $values['placeholder']  = 'ie. 3';
                    // Option 2; Drop down value field
                    //
                    // $values['field'] = 'select';
                    //
                    // foreach ( array( '1', '2' ) as $key => $value ) :
                    //      $values['options'][ $key ] = $value;
                    // endforeach;

            break;
    }
    return $values;
}
add_filter( 'was_values', 'was_values_add_bottles', 10, 2 );


/**
 * Must match quantity of bottles.
 *
 * @param  bool   $match    Current matching status. Default false.
 * @param  string $operator Store owner selected operator.
 * @param  mixed  $value    Store owner given value.
 * @param  array  $package  Shipping package.
 * @return bool             If the current user/environment matches this condition.
 */
function was_match_condition_bottles( $match, $operator, $value, $package ) {

    // Set total quantity of bottles in cart

$total_bottles = check_total();

    // Check if value exists
    if ( $value ) :
            if ( $operator == '==' ) :
                    $match = ( $total_bottles == $value );
            elseif ( $operator == '!=' ) :
                    $match = ( $total_bottles != $value );
            elseif ( $operator == '>=' ) :
                    $match = ( $total_bottles >= $value );
            elseif ( $operator == '<=' ) :
                    $match = ( $total_bottles <= $value );
            endif;
    endif;
    return $match;
}
add_action( 'was_match_condition_bottles', 'was_match_condition_bottles', 10, 4 );

I am having trouble getting the ‘bottles’ custom attribute from the products in cart. I feel like everything else would work once I get that. There isn’t much documentation for this plugin but this is a pretty universal Woocommerce feature, I think. However, I was unable to find the documentation I needed from Woocommerce to go over getting custom attributes from products in the cart.

Thanks for any help that can be offered.