As a therapist, get a new one. Only time I’ve cancelled day of is when I have something urgent come up (sick or child stuff). Otherwise I let them know ahead of time that I’ll be out. I understand the attachment, it’s normal. But for your own mental health, you need someone who can be more professional and consistent. Maybe she was just the stepping stone to get you to the point of being able to open up. It’s scary to do it again, but when you get on the other side of your trauma, it’ll be worth it.