Show the amount of posts in a tag in a specific category has

function wp_get_postcount($id)
{
    $contador = 0;
    $taxonomia="categoria";
    $args = array(
        'child_of' => $id,
    );
    $tax_terms = get_terms($taxonomia,$args);
    foreach ($tax_terms as $tax_term){
        $contador +=$tax_term->contador;
    }
    return $contador;
}