Your test procedure sounds excellent to me. You certainly don't need any outside intervention.
Now try making some enlargements to see if your assessment holds up under magnification.
Remember, you can always burn in highlights if they lack detail on the print, as long as there is detail in the denser areas of the negative.
You can't add detail in the shadow areas beyond what's on the negative. That's why most folks overexpose by some amount v. the film box speed.
It appears you came to that same exact conclusion. Congratulations.