Placing character under a month and year when the month falls between two dates

[gagento]

I am attempting to work out which months fall between two dates. The columns have mmm-yyyy and the dates I am looking at start and end on different dates and years.

I am wanting to place an X in the month columns that reflect what months occurred between the two dates.

[gagento]

This is the formula I have been using with no luck
=IF(AND(COLUMNS($P1:P1)>=MONTH($G2),COLUMNS($P1:P1)<=MONTH($H2)),"X","")