Showing All Taxonomy Terms count based on a given contextual filter
You Did your jobs correctly but you have only one mistake, you should create  views according to nodes then relate it to taxonomy instead create taxonomy view then relate it to nodes.
I explain my mean by example

Nid           title         termid
1           title1       55
2           title2       43
3           title3       55
4          title4        --
5          title6       16     

So when  there is not set termid view has a row result with no termid then this mean you can  put 0 value in  "No result"