It sounds like your therapist may be having some boundary issues of her own. She should not let a 30 minute appointment turn into a 70 minute session, period.

It may help you to ask your T to enforce the pre-arranged boundaries. For example, you could ask her not to let you go over appointment time limits and to ignore emails beyond a certain number. (For example, respond to the first email each week, ignore all further emails.)

If your T cannot maintain a "safe" treatment frame, she may not be the right T for you. To me, it sounds like your T is indulging your 'therapy addiction'. If she's always available to you when you feel anxious, it will be much harder for you to learn to do without her. It's like stocking the freezer of a bulemic with ice cream, and expecting her not to overeat when she gets stressed... It takes a tremendous amount of self-control, and the task would be much easier if the food wasn't so easily available.