All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.
It appears to us that your fasting is valid, and that you do not have to make it up. In this time, in the cities where lights are spread, the Athaan is based on the calendar, because it is not possible to observe the actual time of dawn. Therefore, the break of dawn is not certain based on the calendar only. So if someone ate or drank (after hearing the Athaan), then his fasting is valid because he was not certain that dawn cracked. However, to be on the safe side, it is better that one abstains from whatever breaks the fast upon hearing the Athaan.
Allah Knows best.