I struggle with this also.

I sort of see your T's point, even if it seems sort of harsh and truncated...which is that at a certain point one needs to do things to increase one's self worth. At least, this was true for me. Finding and doing things that made me feel good about myself, made me feel accomplished, was extraordinarily difficult but also extraordinarily helpful. Working, volunteering, completing a difficult task--even if it was just something small like finishing a book I've always wanted to read. Therapy helped my self-worth in that my therapist helped me find those things, assigned them as "homework," and followed up on them.

Therapy also helped me identify unhelpful thought patterns and unconscious assumptions that made me feel like a worthless non-person. Identifying them meant I could bring them to the fore and work on them, decide in session if they were fair or rational. Sometimes my T would model ways to get out of them, or just straight-up tell me when I was wrong.

Anyway, just some thoughts. I hope you find a solution that works for you.