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The bracts should be pink to red in color. However, I did find the following nugget on a university web page that might explain your white bracts - environmental conditions do sway bract color:

"'Satomi' (also listed as 'Rosabella') - This is a very popular cultivar said to develop bright pink bracts. In the United States, however, the warm summers seem to dull the color. As a result, most plants bloom light pink or white-pink. The color can vary from season to season, but 'Beni Fuji' probably has deeper pink bracts."

http://www.hort.uconn.edu/plants/detail.php?pid=125

I wouldn't worry too much yet. Three years is a bit young for blooming expectations. Your tree probably isn't mature enough yet to bloom. Young trees spend a few years establishing their root system before investing energy towards blooming.

For more information on kousa dogwood trees, please visit the following link:
https://www.gardeningknowhow.com/ornamental/trees/dogwood/growing-kousa-dogwood-trees.htm

Are the branches brittle and snap off when bent?
Do they bend? If you scratch the bark does it appear green?
A newly planted Kousa Dogwood requires a good amount of watering in the first 2 to 3 years to become established.
We did have an extremely cold winter in most of the entire United States and a new planting may not have been established enough to survive the temperatures.
Review the care and growing requirements in the article below.
I would provide water and watch and see.
Also most garden centers will replace a plant if it expires in the first year.

https://www.gardeningknowhow.com/ornamental/trees/dogwood/growing-kousa-dogwood-trees.htm

I am sorry but we did not receive your photo. Can you offer more description - how does it look under stress/dying?

In the meantime here is an article on kousa dogwoods that may aid in your identification:
https://www.gardeningknowhow.com/ornamental/trees/dogwood/growing-kousa-dogwood-trees.htm

My dogwood did not blossom too well this spring either due to the cold spring we had - the blossoms are very tender to the cold. Drought could also affect blossoms. These and other reasons are discussed in the following article:

https://www.gardeningknowhow.com/ornamental/trees/dogwood/dogwood-tree-not-flowering.htm

Your soil pH may not be acidic enough; pink dogwoods do best when the pH is below 6.5. I recommend that you test the soil around your tree. To lower the pH you will need to add aluminum sulfate, and you will probably need to do it for a few years at least as pH adjustments happen slowly over time. To get a soil test you can contact your local extension office which you can find using the following link: https://www.gardeningknowhow.com/extension-search/