Expanding a complex IF/AND formula

Hello,
I am creating a stock sheet to count stock in various locations and add up to a total. One problem I've got is that some of the items counted (e.g. napkins) are weighted instead of counted to save time and a weight of one unit is recorded on the spreadsheet. This way I can calculate the number of units from the total weight of a product (e.g. if one napkin weights 0.0018kg then in one kilogram there are around 555 napkins). I've got a formula in the spreadsheet already but it only relates to one location. I'm trying to understand it but I'm having a hard time, basically I need to expand the formula to include more locations.
I'm sorry if this is hard to follow. I'll try to explain as much as I can:

B50 contains this formula: =IF(AND(E50=0,I50>0)=TRUE,"no weight",IF(I50>0,SUM(F50*C50,G50*D50,H50,I50/E50),SUM(F50*C50,G50*D50,H50)))
It only takes into account cells F, G, H and I. I need to expand it all the way to U.
Essentially "full" is a full case and a number of units in each case is specified in "case size". "Sleeves" is a number of packages inside a case and a number of units inside each sleeve is specified in "inner size". "Singles" is just single units counted and "weighted" is weight of a certain number of items in kilograms. The total obviously adds all of it together (in number of units).

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I would appreciate any help to expand this formula as so far I have failed in getting my head around it. I'll answer any questions if my explanation was too chaotic.
Thanks!

Hi Ali,

thanks for such a quick reply! Here is a sample workbook, hopefully this will make it clearer.

Thanks!
Kamila

The categories are fixed, there might be more products added but not in a way that would affect the formula.

Pasted it and it came up with #NAME?.

I completely reworked the original spreadsheet, is it possible that the original formula refers to something I erased? (e.g. the "no weight" bit?)

The categories are fixed, there might be more products added but not in a way that would affect the formula.

Pasted it and it came up with #NAME?.

I completely reworked the original spreadsheet, is it possible that the original formula refers to something I erased? (e.g. the "no weight" bit?)

Sorry, here's the actual spreadsheet I'm working on. There are several sheets but it's the "counts" one that needs the formula.

Looks like it's working! You're an absolute star Ali, thank you so much for your help!

Kamila