How do you know that your work is good enough?
Not to be rhetorical or cryptic, but, you always know when it is.
It’s when you don’t know that it’s probably not.
If you’re asking yourself that question, then, you having poured everything you possibly can into it. You haven’t let your guard down, you haven’t done the research, you haven’t given it your best shot.
When you’ve done those things, there are never any questions left to ask about ‘good enough’.