Have you tried printing the negs or getting a lab to print? With large amounts of white snow in each neg the negs will look very dense and dark or black but you need this to be the case so the prints in the snow areas will be white. The meter records the predominantly white landscape as grey and using this reading the snow will appear grey so using two stops more to get zone VII correct is the right thing to do.

Until you try printing you won't know if the negs have been exposed correctly but unless the snow was only a small area of the scene percentage-wise exposing 1.5 to 2 stops extra is correct

pentaxuser