I am wondering why you were seeing your therapist in a cafe type situation. Is that a regular place for you to meet? There may well be a perfectly good explanation for why you see your t there, but meeting a current t in a public place doesn't seem appropriate to me.

The fact that T followed you into the bathroom is a very clear violation of boundaries to me, and I would have been intensely upset and triggered by that. That could be just my stuff coming through (one of my abusers refused to allow me privacy for bathroom functions, so for me this clearly crosses my boundaries). I have to say though I am REALLY surprised that others here do not seem to see your T following you to the bathroom to *listen*(!) as a violation. To me, checking to make sure you are not purging is not reason enough to violate your boundaries, especially since you had told her you didn't want her to follow you. To me, she did NOT have the right to invade your privacy in that manner.
Did it bother you a great deal? I am not getting why others don't see that as a violation.