sum the total quantity of sale on every 15 days

hi everyone. my query is regarding my stock sheet. in which we add the quantity as we manufactures and we do less as we sales.
so i have to track particular quality with its particular design and with particular shade also. so that i can know which colour is in demand and therefore we can manufacture that. i want to see in every 15 day that how much every colour is getting sold.

for example:- 3rd row (sheet 1)
quality roman design no.1 and shade no. 1 from 1st december to 15 december total sale is of 13 pcs.
i want this 13 pcs in sheet TRACK cell i3.

please do this so that i can run this stock sheet according to my requirement i have a big sheet this is only for query.

so as usual i am hoping this query will also be solved. so thanks in advance.