I do not know how much refrigerant you need. There should be a decal under the hood.

36 PSI isn't so bad for the low-side. Mine runs as high as 2.2 bar on the chart (again, depending on temperature).

Note that you have a variable-displacement compressor, as do most newer cars. The displacement varies depending upon the inlet pressure, which is why it's not taking your low-side line into a vacuum. I would bet that unless it is leaking, your compressor is fine.