Found an answer using Shortcode which helped: How to get Page/Post Gallery attachment images in order they are set in backend using WP_Query()?
My working code now looks like this:
// Extract the shortcode arguments from the $page or $post
$shortcode_args = shortcode_parse_atts(get_match('/\[gallery\s(.*)\]/isU', $post->post_content));
// get the ids specified in the shortcode call
$ids = $shortcode_args["ids"];
$attachments = get_posts(
array(
'include' => $ids,
'post_status' => 'inherit',
'post_type' => 'attachment',
'post_mime_type' => 'image',
'order' => 'menu_order ID',
'orderby' => 'post__in', //required to order results based on order specified the "include" param
)
);
if ($attachments) {
foreach ( $attachments as $attachment ) {
$urlArr[] = wp_get_attachment_url($attachment->ID);
$titleArr[] = $attachment->post_title;
}
}