When you are embedded in a large organisation, your professional identity is partly assumed. The brand does some of the work. The title does some of the work. The organisational context explains what you do, so you rarely have to.
When the context changes, suddenly you are expected to articulate, from scratch, the thing that was always there — but never needed saying. Your editorial through line. The unique value you offer.
You don't lack confidence. You lack clarity. And that has a solution.