Am I overcomplicating this?

I have an automation to create a time stamp in a Date Completed field when a Status single-select field is changed to Done. The Date Completed field is populated with the full date and time, but I need to utilize this information in a Reporting interface for my management so I’d like to be able to have them select the month from a Dropdown Filter. To that end, I’ve created Month Completed field that uses a simple formula to just show the 3-letter code for the month, based on the Date Completed field.

The issue I’m having now is that I’m not able to use that 3-letter code (because it’s a formula field?) as a filter on the Dashboard.

I could create another automation that’ll convert the formula field into plain text or even a single-select field, but I feel like I’ve now created a whole bunch of steps to do something that might be accomplished in a simpler method. 

Note that the Month Completed info isn’t being used anywhere else. The Date Completed will likely also soon be used to calculate the full time it takes to close a ticket. 

I’d love to hear any suggestions on simplifying this, or let me know if this is how most people would approach. Thanks!