I've had major problems with separation in therapy and have had some therapists who don't treat that problem. Separation /Attachment fear IS my problem but I went through some hard-hearted therapists who didn't know how to treat those problems. Everything you feel about attachment for your T is OK and should be a part of gentle therapy. A therapist should sense you have these concerns and lead you softly.

It's important to know what kind of therapy your T does from the start, but many of us don't know those things, and it isn't our fault. You need respectful, gentle inquiry about your attachment feelings for your T and it's very clear that you have feelings which need acceptance, not ignoring, asked to quit a session early, or expecting you to wait months. It sounds like your T only does brief Behavioral Therapy, when what you need is to go much deeper and learn to trust, not fear. Separation Anxiety doesn't automatically stop just because a T thinks a few sessions should do for your case. You're already attached so I know it's horrible to think of separating from this T.

I would try to deal with it by starting to see another therapist at the same time. That could cushion and help with the fear, especially if you can tell the 2nd T about this one you feel so much about. It's a lot easier to get support from another T than go cold turkey breaking away from present current one. I would try to get up the nerve to ask a new T how she handles attachment issues. If she encourages you, then maybe gradually go with her. It's really , really hard when you don't know, can't ask, and are having your heart torn to shreds.