Since there doesn't appear to be any insect or disease problems with your tree, then there may be something going on with the roots.  You should check your tree for girdling roots, which are roots wrapped around the trunk of the tree (at or below soil level) that can restrict the flow of sap in the tree and can cause problems.  It's possible that impacts from planting depth (too deep), too much water, and/or over-mulching took a toll and caused some root loss. It doesn't look like you over-mulched or planted too deeply but it's something to consider.  When the root system is reduced, what remains cannot support the full canopy, so foliage and branches can die off as a result. Until the root system can regrow, replacement top growth may be limited or stunted. Leafless branches should be removed.  For now, avoid trimming healthy growth as this is what is helping to fuel new root growth (and in turn, new canopy growth).

Girdling Roots | University of Maryland Extension (umd.edu)

Continue to monitor the tree for watering needs and soak when needed. Feeling the soil around five inches depth is the best way to judge moisture, rather than going by a schedule or even by the weather (since it can be hard to judge how well a rain soaked in). The root zone should be well-irrigated when needed but left alone when sufficiently moist. If the tree recovers well, as it matures you can gradually correct any aesthetic issues with branching through trimming after flowering in spring.

Thank you for contacting Ask Extension.  Please let us know if you have additional questions.