I was under the impression you could trim this as late as spring and still get blooms? Are you sure this is Annabelle?

Annabelle pruning

Annabelle is in the family hydrangea arborescens. They can be trimmed anytime from fall through early spring and still bloom, and on top of that they won't suffer severe dieback in PA.

You're probably dealing with hydrangea macrophylla. They are not a plant for novices in the north. Trimming, except for cutting off dead branches around June 1, is NOT necessary. You can pinch off growing tips of green branches to make more branches, but they are NOT plants where pruning encourages blooming, because blooms occur primarily on previous year's growth.

Before any long-winded explanations start, consult the link below.

Here is a link that might be useful: Hydrangeas In The North