Excerpt “Read More” link

i think this may solve your problem by removing this condition if ( preg_match('/<!--more(.*?)?-->/', $post->post_content) ) {

Not sure but give it a try

Adds Read More after the excerpt.

add_filter('the_excerpt','openstrap_excerpt');
function openstrap_excerpt(){
    global $post;
    $link='<span class="readmore"><a href="'.get_permalink().'" > read more &rarr;</a></span>';
    $excerpt=get_the_excerpt();   
    echo $excerpt.$link;

}

Following code Limit the length of the excerpt to 20 words

function openstrap_custom_excerpt_length($length) {
    return 85;
}
add_filter('excerpt_length', 'openstrap_custom_excerpt_length');

I don’t why you are using the third function/filter and perhaps not required