How to calculate monthly avergage?

Hi there! I have a pivote table in my quicksight analyisis with orders per product.
I need to calculate the monthly average so i’ll obtain a table like this:

I tried using caculated fields with windowAvg, periodToDateAvgOverTime, runningAvg, etc. It’s not working. Please help!

If these averages are not working you could try:

,[ partition_field, … ]
,calculation level

and then divide this by the count of how many times the value is occurring to get the same result. But actually I believe the functions are mentioning should do the same. How did you write formula? Maybe I can help.