Actually there is considerable disagreement about Ayesha's age. The Haditha which say she was 9 or so were written some 300 years after Muhammad's death. You might want to consider the following facts.
1: Most of these narratives are reported only by Hisham ibn `Urwah (RA) reporting on the authority of his father. An event as well known as the one being reported, should logically have been reported by more people than just one, two or three.
It is quite strange that no one from Medinah, where Hisham ibn `urwah lived the first seventy one years of his life has narrated the event, even though in Medinah his pupils included people as well known as Malik ibn Anas. All the narratives of this event have been reported by narrators from Iraq, where Hisham is reported to have had shifted after living in Medinah for seventy one years.
Tehzibu'l-tehzib, one of the most well known books on the life and reliability of the narrators of the traditions of the Prophet (PBUH) reports that according to Yaqub ibn Shaibah: "narratives reported by Hisham are reliable except those that are reported through the people of Iraq". It further states that Malik ibn Anas objected on those narratives of Hisham which were reported through people of Iraq. (vol 11, pg 48 - 51)
2: Meezaan al-Ai`tidaal, another book on the narrators of the traditions of the Prophet (pbuh) reports that when he was old, Hisham's memory suffered quite badly (Vol. 4, pg. 301 - 302).
3: According to the generally accepted tradition, Ayesha (ra) was born about eight years before Hijrah. However, according to another narrative in Bukhari (Kitaab al-Tafseer) Ayesha (ra) is reported to have said that at the time Surah Al-Qamar, the 54th chapter of the Qur'an , was revealed, "I was a young girl". The 54th Surah of the Qur'an was revealed nine years before Hijrah. According to this tradition, Ayesha (ra) had not only been born before the revelation of the referred Surah, but was actually a young girl (jariyah), not even only an infant (sibyah) at that time. Obviously, if this narrative is held to be true, it is in clear contradiction with the narratives reported by Hisham ibn `urwah. I see absolutely no reason that after the comments of the experts on the narratives of Hisham ibn `urwah, why should we not accept this narrative to be more accurate.
4: According to a number of narratives, Ayesha (ra) accompanied the Muslims in the battle of Badr and Uhud. Furthermore, it is also reported in books of hadith and history that no one under the age of 15 years was allowed to take part in the battle of Uhud. All the boys below 15 years of age were sent back. Ayesha's (ra) participation in the battle of Badr and Uhud clearly indicates that she was not nine or ten years old at that time. After all, women used to accompany men to the battlefields to help them, not to be a burden upon them.
5: According to almost all the historians Asma (ra), the elder sister of Ayesha (ra) was ten years older than Ayesha (ra). It is reported in Taqreeb al-Tehzeeb as well as Al-Bidayah wa al-Nihayah that Asma (ra) died in the 73rd year after hijrah when she was 100 years old. Now, obviously if Asma (ra) was 100 years old in the 73rd year after hijrah,she should have been 27 or 28 years old at the time of hijrah. If Asma (ra) was 27 or 28 years old at the time of hijrah, Ayesha (ra) should have been 17 or 18 years old at that time. Thus, Ayesha (ra) - if she got married in 1 AH (after hijrah) or 2 AH - was between 18 to 20 years old at the time of her marriage.
I have spent well over 30 years of my life studying Islam, talking with Muslims and getting to know their faith. It is important that we take the time to understand their world-view especially if we want them to grant to us the same thing, ie understanding.