You are being a little impatient. Pie cherries usually start bearing
in 4-6 years, and nothing bears heavily when it is young. Add a year
to account for transplant shock, and you get 5 years at the earliest.
Your tree sounds about five years old.

You might also lack pollinators (bees). Self-productive plants may
still need a pollinator to transfer the pollen from the male to the
female parts of the flower (sometimes, they are diffferent flowers on
the same plant).