December 10: Just came across a piece on self-doubt in the NY Times, which manages to articulate the doubts I've felt about doubting self-doubt (!)
As with so much of life, it's a tightrope. Here's article author Mark O'Connell:
"The problem is that the inner critic is actually an indispensable element of any writer's working life; it is the immune system, the necessary resistances against the toxicity of bad writing. Excessive self-doubt is therefore like a sort of autoimmune disease, caused by an overactive and overpowerful inner critic: the cure becomes the condition."