Not knowing enough isn’t the main problem.
No one can have all the answers at all times — it’s an impossibility. It’s a debilitating belief.
Instead, accept that you don’t have all the answers — that no one does.
Not having the answer is simply a your cue to put in the rigor to find it assuming the problem you’re trying to solve is worth the rigor to begin with.
And when you do, you’ll know the next time.