You have a perfectly good Drupal 7 site that does everything you need it to do, but Drupal 7 is nearing its end-of life. If you haven't considered moving to Backdrop CMS, you may be surprised to learn that Backdrop is be your most affordable option -- especially if you've invested heavily in custom code.
Come watch a live upgrade (not a migration) of a Drupal 7 website to Backdrop CMS. You'll get a chance to experience everything that is familiar after the upgrade, and see some of the areas that have been improved. You'll also learn about some of the similarities and differences between the Drupal and Backdrop