12 Month Rolling - Removing future months from calc

[Pmike]

I need help with a 12 month rolling fomula.  The formula I created in DAX as a measure is:

12 Mo Rolling = CALCULATE(SUM('SELL THRU'[Sales Dolalrs]),
DATESBETWEEN(
'SELL THRU'[Date].[Date],
NEXTDAY(SAMEPERIODLASTYEAR(LASTDATE('SELL THRU'[Date].[Date]))),
LASTDATE('SELL THRU'[Date].[Date])
))

This appears to work, however my problem is that I don't want the formula to include anything for future months.  If I have 2016 and 2017 data the formula will add, for example, sales from April 2017 back to May 2016 for April 12 Mo Rolling, however when I get to a future month it accumulates back 12 months but I want to show zero.

Any suggestions would be appreciated.

Thanks,

PMike