I think you may be right about your therapist's power issues being as strong as yours, but you dig this, or you wouldn't keep returning to her to wrestle. She takes your bait, plays your game, locks horns, and you both get bloodied.

Perhaps you could avoid this pattern with a T who was more like water than stone, who would allow you your tantrums but not give them anything to engage. Because if you're anything like me, a tantrum no one engages is a supremely ungratifying thing. And as scary as it is to let go of a primary coping mechanism, I would venture that somewhere in you, you'd like to find the tantrums less attractive and useful.