Measure for Difference in Same Column From Filter

[lac0403]

I have a Cost file in my data model that has costs in it for different times - Last Year, This Year. I have a measure

Difference Last Year - This Year = Calculate (Sum ('Cost File'[Last Year],'Cost File'[Period] in {"Last Year"})-Calculate (Sum ('Cost File'[Last Year],'Cost File'[Period] in {"This Year"})

The measure calculates fine in the pivot table, the problem is I want to see Last Year, This Year, and the Difference columns. But in the pivot, it shows the Difference column twice.

I am just learning DAX. I think I need more in the measure DAX code, but do not know it well enough. (And all reference is online.) Any assistance is appreciated.

Using Excel O365 Desktop / Power BI Desktop for the power query & data.