What do you know about where it came from? It may have been shaded by a larger tree or building and grew out towards the sunlight.
Also, how long have you had it? Kousa (Chinese) dogwood are mostly resistant to verticillium wilt, but White Flowing dogwood will get
wilt disease. Both like drier soils, not wet feet also.
Edit- Also, when it flowers, you will be able to tell if it is a Kousa or another type of dogwood by the flower pattern. Gray and Silky dogwoods are shrubs and not tree forms.