Unusable or tank capacity?
Kudos for running the test, Ron. I think you really want unusable, and fuel tank capacity. Right? Unusable should be done at cruise, nose down, and stall(or go-around) nose up attitude. It sounds like you are running the test properly, you could restrict the boost pump output to the max/min fuel pressure and measure flow at the same time to validate it's performance also.
If it is like the 10, there is very little unusable fuel, but it is sensitive to wing level. That test will have to be run in a flight test to ensure you will not run out of fuel in uncoordinated flight on landing.