Few blooms on rhododendrons are most often due to lack of sun or lack of water in the fall when blooms are forming for the following year. You can prune it now but this will not guarantee more blooms. I suggest you make sure it is watered at least once a week this summer. In early spring such as when you see the forsythia in bloom apply a Rhododendron and azaleas food around the root zone of your rhodie. If you don't have flowers next spring move the shrub to a location with more sun or in a more protected location if you live in an area with cold winds and freezing winters. Keep growing, Marianne Binetti