There’s one rule I obey when hiring people. When I have any doubts, the decision is “no hire.”
I’ve seen several times hires which were made, even though there were some doubts. It was never a very good decision. Just a good one if we were very lucky. On the other hand, I don’t remember any situations when we were sure the one would suit us and, at the end of the day, it appeared that we were wrong.
Sure, you’ll never meet the perfect candidate, but it doesn’t matter when you feel the person will be good. Trust yourself. You’ll know. You’ll feel.