So the main point ... you don't get the film speed from the lightmeter setting. When you do film tests like this...
You get the film speed from the box. The rated speed of fresh film in a standard developer, is very close to the "speed" of the curve that has an 0.62 average gradient.* So take that as "Zero" - your other speeds are relative to that box speed.
When you develop less, you get less speed. Develop more and get more speed.
*I see Ralph suggests 0.57 - close enough for you to use his numbers for practical purposes.