When she comes over, she will bring it up and l will kindly ask her, " have you spoken to your mom yet?" 

She will say lie at first but then say no. So then I tell her the same thing aforementioned the first time. 

Should I just tell her? Clearly she's uncomfortable speaking to her mom about things and I understand why. I want her to be aware of her body, because she's thinking she diarrhea her pants. Her mother started her period at 9, so there's a huge chance she will be starting soon. I am well educated on this matter and since my sister is more comfortable and listens to me, I figured me telling her can't be harmful, I prefer to get yelled out than have her think that somethings wrong with her. She needs a trusted adult to speak to about sex, friends, periods and life. I am non judgemental and try to be very understanding so I see why she trust me.

The reason why I am unsure if I should tell us because her mom doesn't let her wear shorts, skirts stick her tongue out because it's too sexual. So in other word her mother has over sexualized this little girl. So she's not comfortable speaking to her mom and I feel bad for her. Don't know what to do, thinking I should talk to her mom myslef.