Remember that 'feeling' incompetent is not the same as 'being' incompetent, and it is often about fears we have. Feeling overwhelmed is exhausting. This might be a hard time to be attempting to step up your game. Maybe it would be kinder and feel better to be easier on yourself right now. Is it possible to talk to your boss about this, with the emphasis on wanting to be competent and capable and any suggestions that person might have.

I can so relate to what you wrote. I hope you will talk to your therapist about this too