Trying to include a custom field code into a function

Caveat: I’m not a programmer! : )

Ok, so, through much searching I’ve put this function below together to create a shortcode so that my client can specify which posts she wants on the homepage. So all she has to do when she wants a particular number of posts on the homepage is put this [featured post=322]. Here is the code I used:

[Code moderated as per the Forum Rules. Please use the pastebin]

Now sometimes there is a credit for a photographer that will go under the author byline. So I found this bit of code below for a custom field that will only show if this custom field is used. If I don’t use this custom field nothing appears in the post or archive pages, which is good. Here is this code:

<?php if( get_post_meta($post->ID, "photographer", true) ): ?>
	Photos by <a href="<?php echo get_post_meta($post->ID, "photographer_link", true); ?>"><?php echo get_post_meta($post->ID, "photographer", true); ?></a>
<?php endif; ?>

What I need help with is how do I get that photographer custom field code into the featured post function underneath where the author byline is? I can add this in

$return .= '<div id="featured-wide-author">Photos by <a href="'.get_post_meta($post->ID, "photographer_link", true).'">' .get_post_meta($post->ID, "photographer", true). '</a></div><br />';

which works but of course the “Photos by” will always be showing whether or not I use the custom field. Basically I need the if/endif part to be in there.

I hope this makes sense and I hope someone can help me with this. Is this even possible?

Thank you.