A lot of teen girls aren't self confident because of what other people say or think.
But I say why do you care ?
Like honestly, think about it.
Why does their opinion matter to you.
If they are not doing anything to benefit your life then I really don't think you should be concerned about how they view you.
I know this is easier said than done and that it can be hard not to let it get to you.
However I try to live by a mantra that says "If you don't like something about yourself either change it or if you can't or won't change it then learn to love it".
This really hasn't let me down so far.
Almost all the insecurities I once had I now love and the ones I don't love I still accept and live with.
Because at the end of the day I'd rather live an imperfect life with my flaws than an unhappy one when I can't love myself.