Another version which indicates that Aisha was older:

"Muslim authors who calculate Aisha's age based on the more detailed information available about her sister Asma estimate that she was over thirteen and perhaps between seventeen and nineteen at the time of her marriage.[28] Muhammad Niknam Arabshahi, an Iranian Islamic scholar and historian, has considered six different approaches to determining Aisha'a age and concluded that she was engaged in her late teens.[29] Using the age of Fatimah as a reference point, the Lahore Ahmadiyya Movement scholar Muhammad Ali has estimated that Aisha was over ten years old at the time of marriage and over fifteen at the time of its consummation.[30]"

From Wikipedia