Trying to create list of featured posts to display on single page

Here’s roughly what I’m working from. http://pastebin.com/kpXexTBa

Obviously there’s another function in the single.php file that references this. If I put the code within the loop, it goes nuts and affects the post being displayed. However, if I put the code outside the loop, it displays as intended. How do I make this function work independently and not wreak havoc with other posts?

Yeah, that’s the function. What I’m trying to do is inject it into the content, after the second or third paragraph to show some featured posts we’d like to highlight.

At the moment, I’ve manually inserted the code, but I’d like to automate this using a filter method like this: http://www.wpbeginner.com/wp-tutorials/how-to-insert-ads-within-your-post-content-in-wordpress/