Many camellias grow very slowly. That is the reason for the high cost when you buy espaliered ones or very tall ones. I may notice just a few inches of growth a year. Others grow faster than that but even then, I am not talking like roses do. Below is a link to an article on fertilizing camellias with a suggested fertilizing plan.

Here is a link that might be useful: Camellia Fertilization Article by the ACS

Hi Max,
I grow a lot of the Cold Hardy varieties even though I don't live in an area as cold as yours. I have noticed a huge range of growth habits and rates among the different varieties, so it is possible that there is nothing wrong with your 'Frost Princess'. If the color of the foliage is dark green and the plant appears to be healthy, I would not be too concerned. It would be nice to hear from someone that has actually grown 'Frost Princess' and could tell us if there are problems associated with this variety.

Here is a link that might be useful: Cold Hardy Suggestion from Dr. Ackeman

In zone 6 and 7, it's better to fertilize lightly one time in spring only. Slow growth is better than growth that gets frozen back. Small camellias will grow faster after about 3 years in the ground while 2 and 3 gallon plants establish in a year or two.