Since I am in such a different environment, I'm not sure what to tell you :-) But like Hydrangea macrophylla, H. quercifolia blooms on the previous year's growth and these buds can be damaged by excessive winter cold as well as late spring freezes. And in my area, these are mid to late summer bloomers, so I would not expect to see flowers until well into July.

fwiw, my 'Little Honey' never lost its leaves over winter. And while oakleafs DO hang onto old foliage for an extended period, not to lose any is a bit much!! I actually had to manually pluck the old leaves off and there are still some persisting in the interior of the plant.