I've been told that sometimes you feel worse before you get better. The dissociation probably numbed you out to help you survive, but the therapist is supposed to help you actually deal with your pain/emotions so you can get through and past the pain so it no longer controls you. At least that is my understanding.

Probably if you go bra shopping and nothing bad happens, it will cease to bother you in time. Your body will adapt to the new situation. If you avoid it, the old associations will remain.