You can create two variables with the correct dateranges before doing the xpath.
So create a datetime variablle using addMonths([%CurrentDateTime, -1)
And one using addMonths([%CurrentDateTime, 3)
And use these variables in your xpath.
I believe the condidtion in an xPath always needs to be set in square brackets. Meaning it should start with [ and end with ]. Your 'and' connector can just stay within these brackets. You cannot do [...] and [...] but should rather do [ ... and ... ] Hope that helps