tba just being started, though some possibly useful ideas:
Doubts are insidious. Don't allow them to persist. Deal with them right now. Never let one go unaddressed.
Write them down.
And then examine them for their truth or untruth, because doubts are mostly beliefs.
I doubt myself because
beliefs about myself
I got this at this age from person, situation
Is it true? Absolutely? Or is it some left over pattern? (See Brain Patterns write-up.)
Although you cannot guarantee any outcome that you do not control, what else about you do you believe in this instant.
Not being sure of an outcome is no problem. What is a problem is doubting yourself or underestimating your ability...
distrust of sef or wrth
lack of conviction, uncertainty
lack of trust or confidence
apprehension or fear
doubtful - not clear or definite