I am seeing the same strange behavior every year with a cherry tree that is ~8 years old. Here's what happens:

1) In early spring the branches are all alive and full of buds which all progress to healthy blossoms.
2) A few weeks after blossoming, the petals fall off normally and leaves begin to emerge.
3) Most branches never develop full leaves along their length, just at the tips of the branch. Most of the blossoms (~90%) do not produce any fruit at all. The remaining fruit is mostly weak with a few healthy cherries. Some branches completely wither and die.

Here are some pictures to illustrate what is happening:
https://goo.gl/photos/TbWSSe4saoi2ysYt6

The tree limps along and seems to do OK over the summer, except for some slug-like grubs that attack. Last year I manually cleaned them off and the tree seemed to do a lot better with more healthy leaves and branches, but after blossoming, the same problem.

As you can see from the pictures, the back yard is somewhat shaded, but the tree gets 3-4 hours of direct sun each day (when it isn't cloudy - I'm in the pacific northwest). Would this cause my tree to be unhealthy?

Any ideas what is going on?