waterfall chart by period

Hello I would like to have a periodic waterfall chart, for each month I get the visual below (here it's an example for one month). Unfortunately when I try to break down the graph by month I don't get the expected result. 

Here are the data (delta_type is the first column, and total2 is the second column) I would like to have the sum of my kept, lost, and new for each month (second column)