Hmmm...to me 11 most definitely is a little girl. I'm pretty sure she's not being teased.
2 things. First of all, I agree that 11 is a little girl. She may be growing up, but she is a baby in so many ways. Second thing, she may be embarrassed even if she is not being actively teased. My DD11 was. I don't know why. I also had a rule-summer before 12th birthday- which makes sense for Fall babies like mine, but I rescinded the rule when I realized how upset DD was.