First of all, there is uncertainty over what age Aisha (ra) was at the time of marriage to the Prophet (saw). but yes she was young. now you see your lack of knowledge has once again defeated you in your aim to shame Muhammed (saw). Let me lay it down simple for you.
2000's - in this society we believe the "right" age to marry is in our mid to late 20's and early 30's. ..is it really right or merely just an evolved culture? eiether way theres nothing wrong with that.
Only a few centuries back, if a girl was in her 20's and unmarried she would be frowned upon. Society believed the age was to old for marriage. the gap ages between a husband n wife were also much more bigger...it was the norm then, but now we think its backward. give it a few centuries and our society will be backward to the future idiots..but we think its pretty damn good, modern etc etc.
The point im trying to make is, that in the time of prophet muhammed, it was a COMMON thing for girls who reached their puberty to get married to men. as soon as a girl started her mestruation she was considered, and became a women-all this teenage crap is new and was never their before. this is a fact, not my own theory to prove something to myself.