Help! Calculating stock levels with short expiry, regular deliveries and demand

Hi all, newbie here!
I need a workbook where I can enter delivery dates, regular stock demand and if stock has been transferred. The stock has a very short expiry of 3-4 days so if we know we are going have surplus stock, we will ship to a different site, or vice versa.

I've attached a sample sheet, where I started with a sumifs statement but then realised because deliveries/demand will overlap it wasn't going to be that straight forward.

Any suggestions would be most welcome. The end user originally had their spreadsheet with dates running horizontally. So if it could be done this way that would be very helpful too.

Many thanks in advance!