I rearranged your data a bit. Your actual data is in the top four rows.

Below that I have YTD data, but double the number of columns, because sometimes it helps to make the data crazy so the chart comes out right, and easy.

The formula in B7, copied into B7:F8 is:

=IF(INDEX($B2:$F2,B$6)=0,0,SUM(INDEX($B2:$F2,1):INDEX($B2:$F2,B$6)))

This gives a YTD only if the current month is nonzero.

The formula in G7, copied into G7:K8 is:

=IFERROR(IF(INDEX($B2:$F2,B$6+1)=0,0,SUM(INDEX($B2:$F2,1):INDEX($B2:$F2,B$6))),0)

This gives a YTD only if the following month is nonzero.

The formula in B9, copied into B9:K9 is:

=SUM(INDEX($B4:$F4,1):INDEX($B4:$F4,B$6))

Then I selected A6:K9 and inserted a stacked area chart (Chart 1).

I changed the chart type of the Target series to a line (Chart 2).

Then I formatted the horizontal axis, and changed the axis type from Automatic to Date (Chart 3). I could get away with this because the X values were numerical. Excel plots all values for a given date a the same point along the axis, and it sorts the data by X values first. So the X values are plotted 1,1,2,2,3,3,4,4,5,5. And at X=3 we have a YTD value then a zero value, at the same horizontal point, which makes the vertical cutoff we need.