What is the ruling on hesitating to complete the fast after stopping the suhoor a minute before the dawn adhan, with doubt about the accuracy of the adhan's timing?

Your fast is valid as long as you are not certain of the dawn's break at the time of your suhoor, and the default is the continuation of night until the break of dawn is established with certainty. Your hesitation in breaking it or changing your intention to a supererogatory fast does not invalidate it. And fasting to make up for Ramadan is sufficient in this case.