Typically Kwanzan cherry grows wider than it is tall.  I believe that given time and maturity your tree will begin to spread out in the fashion you describe and become more like what you are looking for.  It is possible to get it to spread out more.  You can do this by placing spreaders between the branches (pieces of lath with a notch cut in each end that can force the branches in the direction you want), or by using string tied to a stake to pull the branch downward (just be sure not to girdle the branch).  Trying to force the tree to produce new branches lower on the trunk is theoretically possible, but I don't think it would improve the appearance of the tree.  Mostly I think you just need to be patient.  It looks like a beautiful tree so just give it time to assume its mature form.

Thank you for your response.  It is very helpful!