JMO, but it's not just the AA definition of sobriety, it's any definition of sobriety means totally abstaining from all alcohol and other mood-altering, idk, stuff. Maybe this isn't a technical definition but it's always been what I understood it to be.
If this therapist has threatened to cut off the therapeutic relationship altogether... well I think that is a form of bullying and puts you in the position of deciding whether you should lie or find a new therapist. But maybe you should tell her the truth and then decide if you need a new therapist.