Waterfall by month

Hi - I want to create a waterfall chart which shows forecast sales by period (month) over a financial year. I have the tables loaded in with the financial periods as a column and sales in another column. the x axis sorts in order of sale volumes i.e., the period with the highest sales is first, as opposed to P1. I have tried using the default waterfall graphic in PowerBI and also downloaded "simple waterfall" - both look the same. I have tried renaming the periods 1-12 and formatting them as a number, i have tried sorting the column also, but nothing changes the order, so it looks like the below picture.