@FUBARFlossie I relate to this so so much.
I was told in my 20's I have PTSD from childhood events, sought counselling and had overcome the more 'obvious' problems arising from it. Despite this, I'd always felt very capable in terms of work and just life in general, that is, until the end of 2018 when I had a complete breakdown after having endured some horrible treatment from family (ironically DH's family, not even my own).
During this time I really struggled with work, constantly doubting myself because my concentration was shot from months of poor sleep. I ended up taking time out and going on antidepressants for a time, but I can't say I've yet gotten back that confidence that I previously had despite being promoted at the end of last year. I still constantly ask if what I'm doing is right even when I'm 99% sure myself, I just need that reassurance.
I'm no longer on antidepressants because we are TTC so I'm doing my best to work on myself as much as I can. I've done some reading up on imposter syndrome and I listen to podcasts on personal development daily to give myself a boost. I am really hoping that over time I will gain back some more of the confidence I once had.
The really strange thing is...I KNOW I'm capable and I do try to remind myself when I'm feeling anxious, it's just the feeling of inadequacy is often stronger at those times.
Keep building yourself up as best you can OP. I know at my worst, I could only speak and think negatively of myself but I'm now in a place where I'm able to cut myself some slack and not best myself up so much and I honestly think its the answer. It just unfortunately isn't a practice you can switch on, you have to challenge what you tell yourself again and again until it changes.
What else is going on in your life right now that couls be supportive or indeed unhelpful to how you are currently feeling?