Oh, another antidote that I have found to be very powerful, is to be brave enough to share these feelings, first with very friends (and strangers on MN) and increasingly with others in your field.
If you can put yourself out there, not to show yourself as anxious, just matter of factly mention that of couse, you have those feelings of never being good enough, you will be pleasantly surprise by quite how universal they are.
I thought at first that they were just me, then just my close confident then women I am close to them on a management development course I discovered that almost everyone has 'em. The more confident seeming, the more likely to have that voice in the head whispering or screaming 'not quite good enough'.
Interesting that you are more comfortable with smaller victories.
The fact remains that you are absolutely enough. You are exactly right as you are at this moment. I'm not religious but I do think it's true that we should 'consider the lilies of the field that toil not, neither do they spin. They just get on with being
You can also grow and develop which can be uncomfortable. You don't need to do so but are free to, if you so choose.
You are absolutely enough, just as you are.