look up Aisha's older sister Asma who was said to be 10 years older than and also said to be in her late 20s during Muhammed's marriage (according to sirah and tabaqat), meaning Aisha wasn't a very young child. her age is very unclear and obscure because of the contradictions. but she fought in battles, that's bizarre for a child and slightly more normal for someone in their late teens. also she had children, giving birth as a child is possible but is very dangerous and very likely to end in death, I don't think it would be so normal.
historical facts can and do get distorted, sadly. it's not easy to preserve very little subtle info like that.
P.S by agreeing with Sahih Al Bukhari, you're also accepting that Islam isn't a violent religion. thanks for reading.