This happens to me too, and I think it's quite common. For people who have a history of using unhealthy/self-destructive coping mechanisms, it's natural to gravitate more towards them when you become more emotionally vulnerable (i.e. talking about difficult stuff in therapy).

The beginning of a new therapy relationship is really intense... retelling your life story to someone you just met, bringing up all your old issues to the surface. The first month with my new T, I experienced a spike in ED symptom usage (which was already quite high to begin with). It wasn't until several weeks in that we even tried to start dealing with those on any concrete level... because the first several weeks she was just trying to learn everything about me and my past. I'm going on month 4 now and things have settled a little bit... but I also have a weird tendency to get uncomfortable with any level of progress, so it is usually an up and down kind of thing.

^^This too. I think on some level, I knew the first month or so with my new T we wouldn't be so focused on actual symptoms, so I kind of used that to my advantage. As an excuse to have one last Big Hurrah of Crazy! oh, if only it really WAS the last big one...