Aggregate data with Sheets pivot table or graph

Question

Please have a look at this google sheet here.

It has a pivot table with 3 columns:

A period (for example: 2016/01), a category and a number. I would like to do a chart that looks like this:

For each period, have a breakdown of the number for each category (one bar for each category).

Unfortunately, every attempt failed so far since I can't even aggregate the data properly in the pivot table:

As you can see, the same "period" is repeated many times even within the same category. The same happens with "category" - it doesn't aggregate the data.

Should I fix the pivot table: if so, how? Or should I just ask the bar graph to aggregate the data? So far, any attempt hasn't worked and only displays scrambled data.

I'm sorry this question sounds a lot like "please do this for me": as you can see, I've managed to aggregate the data properly in the sheet "Simple pivot table". However, as soon as a third variable is added, I'm completely at a loss.

Answer 1

Pivot table was wrangled because of how I compute Period. It used to be just a copy of Date, I'd then use Sheets Data -> Number -> Format to change how it's displayed (removing the day, leaving just month and year). This is a stupid workaround since the pivot table knows the underlying data, even if the cell doesn't display it.

Replaced this trick with =TEXT(DateCells, "yyyy/mm") and now the data properly aggregates.