If you mean you want just count variables, you could do the following.
Create a variable with value [Start of month]
Perform a retrieve with created date > Variable and then you count.
Then you set a new variable with value addMonth([Start of month], -1) to get the start of the previous month.
You can then retrieve with created date > new variable and < old variable.
You can repeat the last part, moving the 2 variables in time. When your retrieve gets 0 results, you stop looping.
This only works if every month has values.
If not, you need to also check what the total count is and keep adding the values to check wether you are done.
Does this make sense or work for your issue?