Last n months formula but respects leap year dates

Hi,I have a spreadsheet with dates powering a pivot table with a chart to show the last 12months worth of data - whatever data I have in there it should just show last 12 whole months. I had a formula which determined if a date was in the last 12 whole months and it worked fine until this year when Feb 29th came along (leap year!)

See my attached sheet for the EO month formula I was using.

Does anyone know a formula to determine if date was in last 12 complete months which can account for the 29 days in Feb this year? I have tried search but cannot locate the answer to this.

Your help is much appreciated