Pete, I presume the quick test was done with pseudo-isochromatic plates (where you try to see the numbers hidden in a bunch of polka dots). This is a very rough test when given in the GPs office, good for finding gross problems only.
There actually is a fairly good test that can be done on your computer, which will identify color discrimination problems. The software is not expensive, but not free, however, so you may not want to bother.
http://www.visualmill.com/shop/catalog/index.html
Even this will not tell you if you have color mixing curves within the normal range, just if you have color confusion on certain hue axes; complete characterization of color vision takes something called an anomaloscope:
http://4colorvision.com/files/newnagel.htm
The basic principle of this is to present an actual yellow wavelength of light, and for comparison, a mixture of red and green that can be adjusted by the subject until the mixture appears to match the "real" yellow. The ratio of R/G and the total amount then define several types of long-wavelength or mid-wavelength color defiiciency. For example, if the subject in repeated trials selects a wide range of match ratios, it may indicate a lack of discrimination between red and green hues.
As the web page explains, recent versions have also been developed to measure short-wavelength deficiencies by matching a cyan wavelength with a mixture of blue and green.
You are actually doing an anomaloscope type of experiment on yourself if you try to adjust the R, G and B drives on a monitor to match a given external color (which has a different spectrum from the mixture of phosphor spectra that reproduces it).
Visually matching the screen white point to natural daylight has some of these aspects to it, but I note two things:
1) the R/G vs. yellow and G/B vs. cyan measurements involve only two variables each, so are much easier to do
2) sensitivity to hue is much greater at higher saturations, so the variance in measurements of your vision would probably be huge for data derived from white point settings.