Help with creating New Measure

I have a table I am working with to make Waterfall just like this Excel sheet 

I need to make few new measures before I can make it like look it excel sheet.

This is how my PowerBI looks like. 

The total numbers at the top matches to excel #issues numbers but the problem is when I choose each month, it gives me the count for that month. I want to subtrack the count of the month from the total and show the results.

For example, this is for month 0, I want to subtrack 564 from month Feb from total which is 21,163 to show in the next line.