I’m not sure I 100% grasp what you’re trying to do, but I believe using WordPress’ default Gallery shortcode is what you want. When you insert an image into the content using the “Add Media” button, you can create a gallery and say how many columns you want the gallery to be.
If mark-up doesn’t line-up well you could always repurpose the shortcode with your own mark-up, by using remove_shortcode( 'gallery' ); and then coding up your own function and doing an add_shortcode( 'gallery', 'my_gallery_shortcode );