Here's a video that might help - https://www.youtube.com/watch?v=QgGcg5uvAyI
This article has a lot of great tips: https://www.southernliving.com/garden/grumpy-gardener/why-your-hydrangea-didnt-bloom
Might possibly be related to your planting zone seasonal conditions. Was your winter spring temperatures quite cold —it’s possible these conditions may have destroyed your blossoms for this season. A different cultivar might be suggested. Please refer to the links below. I hope this helps.
In summer, branches produce new buds for the next spring. These buds stay dormant all winter and bloom in spring. If winter temperatures got too cold, or if there is a spring cold snap that kills the buds, non-reblooming Hydrangea macrophylla will not produce flowers that year.
There are hundreds of bigleaf hydrangea cultivars in
the trade, however, aside from flower type and color, the principal cultivar selection criteria is cold hardiness. Bigleaf hydrangea is rated as a zone 6 to 9 species; however, the shoot system (leaves, stems, and buds) of many cultivars are not hardy in zone 6 (areas west of Roanoke, Virginia), where average minimum tempera- tures for zone 6 are zero to minus10 F. In general, tem- peratures below zero F will kill flower buds as well as well as stems, but new stems may be regenerated from roots the following spring provided that the low winter temperatures did not kill the root system. Flower buds, but not necessarily stems, can be killed in thee range of zero to 10 F.
I use SuperBloom on all my flowering bushes for getting them to bloom and get bigger flowers.