Table to summarise data into a spreadsheet

I have the following table in excel

[Base Date]

I have tried a number of formulas to get what I want such as:

=IFERROR(INDEX($H$1:$Z$1,MATCH(TRUE,INDEX($H2:$Z2>0,0),0)),"")

This returns the number 6431 which is correct, but what I need is to calculate a table which would look like something as follows:

[finished data set]

There could be zero, one or multiple values in each row, all adding up to the total in Column D.