If you make the best decision with the information you have at hand you shouldn't regret the decision you make. Retroactively the decision can turn out to be a mistake, but those mistakes you can easily accept: at the time you believed you made the right decision.
There's no need to second guess yourself, beat yourself up and ask "What if?". You can make a decision and if it turns out to be a mistake, just say "whoops" and move on.