I had read about my shadow being an ESTP but, it hadn’t really clicked. I’ve been referred to as a grumpy ISTP by INTJ friends. I usually don’t become more outgoing when I’m stressed. Then I had one of those “A-hah!” lightbulb moments. It’s not a matter of being an extravert or an introvert it’s Ti before Se or Se before Ti. Reading on INFJ and ENFJ in the Recognising Stress” section, shows a bit of that difference.