Measure scenario...is it possible?

Hello,

At the Business Applications Summit back in July it was stressed that one should try to always use measures instead of calculated columns, so as not to bog down the system.  I have a scenario that I've been unable to create a measure for and I'm curious if it's even possible.

Here is the scenario:

We have a forecast each month that extends from the current month till the end of the year.  So the 2018 October Forecast is from Oct to Dec.  We want to compare forecast versions, but it's not apples-to-apples since the October Forecast is 3 months whereas the January Forecast would be for 12 months.  Therefore, I need to create a scenario in which each forecast month includes actuals from the prior months.  So the January amount (12 months of forecast) could be compared against the October amount (3 months of forecast and 9 prior months of actuals).

I have already solved this using calculated columns in a matrix, but I needed to create a separate column for each month.  12 calculated columns.  I would love to streamline this into a single measure. 

Here is the my DAX function for the October Amount calculated column...

October Amount=
IF ( OR ('DATA_TABLE'[FORECAST_VERSION] = "10 Oct",
AND ('DATA_TABLE'[TRANSACTION_PERIOD] < 10,'DATA_TABLE'[FORECAST_VERSION] = "ACTUAL")),
'DATA_TABLE'[SALES_AMOUNT],
0
)

Any help would be appreciated.  Thanks!