We can definitely get your Amber Wave Ninebark to bulk up and fill in! However, it will be best if you wait until early spring next year to work on it. Next spring, before it starts growing leaves, cut your ninebark back about a third to a half. This will force the ninebark to put the energy into growing more branches. Watch my video on pruning hydrangeas to see how it’s done. The pruning method works for ninebarks too.
Thanks for writing!