โ€”โ€” on Aisha (7/9)
To get a more precise age, we can also turn to the Seerah. You see, Aisha had a sister, Asma ibn Abu Bakr and in a lot of Seerah, particularly in Al-Bidayah wa al-Nihayah by Ibn Kathir, it is said that Asma died at age 100 at 73 AH and that she was 10 years older than her sister Aisha.

This means that Asma would have been 27 at 0 AH. It also means Aisha would have been 17 at 0 AH, making her be around 11 when her father fled to Ethiopia and 19 or 20 when she moved to live with Muhammad.