Comparing months with the same selected period

Hi people,

I'm having a little trouble getting the following result: I'd like to get the amount of leads for the current month, the previous month and the month before the previous one according to the period I select. I want to know what was the amount in the same period in these 3 months. How could I do this?
Here is the result I would like to get,

I am using the following measure and it is not working

    var atual = CALCULATE(DISTINCTCOUNT(_leads[Id]),_leads[Produtos com nome do Reaal]<>BLANK())
    var delta = DATEDIFF(max(d_calendario[Date]), min(d_calendario[Date]), MONTH)

    RETURN
  CALCULATE(
            atual,
            DATEADD(d_calendario_aux[Date],delta-1, MONTH)                    
             )
   

Here is my PBIX attached:

https://ufile.io/nl9o9xon