Try this on your own and tell me it isn't frustrating. I'm trying to use the Month field between to Freemform Tables. I want 2018 under a segment in one and 2019 in another. However, Workspace doesn't work this way. For instance, if you create a Panel that spans 2018 thru 2019, then create your two segments, one for 2018 and one for 2019, you will get a Charlie Foxtrot as a result. Instead of the months of Jan - Dec of 2018 underneath one and their respective months for 2019 in the other, it gives me 15 months for both, starting with January 2018. CRAZINESS!
In order to get what I want, I have to create two separate panels, set the year for each and then go after the data. The problem with this is that I cannot compare and contrast the data next to each other in graphs or otherwise. SUPER FRUSTRATING.
Unfortunately, there is no satisfying "correct" reply that can be applied to this one, because this is a problem that cannot be fixed in the current way that Adobe Analytics currently behaves. I played with this for more than an afternoon using all of the suggestions and was unable to produce output the way I would have preferred for it to display in the first place. I used a workaround and moved forward. Thanks to everyone for their efforts!
I would recommend defing your year just as you did (or using the year dimension), but instead of dragging the month dimension in, try using month of year. This way, you should be able to get rid of the months outside of the defined year date range.
As indicated in my screenshot's annotations, the "Month" is based on the panel's date range. For example, if I changed my date range to start from 1 Aug 2019, then I'd get this:
But it's worth noting that the data is still correct. Notice that only the 2019 months have non-zero numbers (which I've grayed out).
I think @pier-olivierd92's suggestion is the best option for you. But as you've noted, and as I've indicated in my first screenshot's annotation, "Month of Year" is treated as a string, and its values are added (seemingly) randomly. So if I were you, I'd do the following:
Click the "Month of Year" in the left rail to show all of the month names.
Drag the missing months into the table as columns.
Rearrange the months to be in chronological order.
It's also worth noting that you can right-click in a metric and choose "Compare time periods" or "Add time period column" that can maybe ease your work, as @evolytics_brian suggested.