To be honest, I'd actually do this way different. I've attached a version using a PivotTable to do the work for you. Entering data in your table (the Data) page, will look a little different, but once you go to the PivotTable, right click it and select Refresh, I think you'll find it's pretty slick.
I also put in slicers to control the date/week as well as the PivotTable page fields. Not sure which version of Excel you're using, so you may not see the slicers.