posting image in worpdress only if they have * in caption - php

Question

This is what I have now in my page-name.php:
<?php
$args = array(
'post_type' => 'attachment',
'numberposts' => -1,
'post_status' => null,
'post_parent' => null, // any parent
'post_mime_type' => 'image'
);
$attachments = get_posts($args);
if ($attachments) {
$attachment_meta = wp_get_attachment($attachment->ID);
foreach ($attachments as $post) {
if ($attachment_meta['caption'] == 'Ceahlau' ){
setup_postdata($post);
echo wp_get_attachment_image( $attachment->ID, 'full' );
the_attachment_link($post->ID, false);
}
}
}
?>
And this is what I have in functions.php:
function wp_get_attachment( $attachment_id ) {
$attachment = get_post( $attachment_id );
return array(
'alt' => get_post_meta( $attachment->ID, '_wp_attachment_image_alt', true ),
'caption' => $attachment->post_excerpt,
'description' => $attachment->post_content,
'href' => get_permalink( $attachment->ID ),
'src' => $attachment->guid,
'title' => $attachment->post_title
);
}
$attachment_meta = wp_get_attachment($attachment->ID);
Can you please tell me what is wrong with my functions? I want to post image only if they have "Ceahlau" in caption.