Hi there, I felt that maybe I could help out a bit by responding.
As you, I was in total shock the realize that todays girls are just growing up too soon. I didn't waer makeup till I was 25. At the time I was working at a children's fashion store and had to make purching desitions and be open to what todays girls look for. Therefore I realized how even the little girls start to get the peer presure about how to look and ack like the other girls. Not all kids are as futunate to have a strong relationship with their parents and the reality is that our kids that do talk to us, spend their time with these other kids all the time
I have a daugther of 13, therefore I know what you are going through. I'm no expert but maybe my experence can help you a little.
I divorsed her dad when she was small, so she and I have strong bond and friendship we talk alot about everything.
At the same age of 11 is when she did exactly the same thing mascara and lip glose. I told her no mascara. But at times Id find out that she still did it at school because I have good relationships with her teachers. So after compromising with her we decided to only do the clear mascara and lipglose and ok. I thought that if I can't stop it I could monitor it. But of course it didn't stop there.
When she started middle school my sweet lil girl did a full 360 on me from a pink princess to an Emo chic.
Black makeup all over! I was in shock to say the the least.
I took it as a phase and just realy had a hard time with the black eyeliner so again I found myself compromising. We said that she could only do it on occasions. And I was lucky, because it was just a phase and she doesn't do it any more. She realized that she realy looked bad instead of cool.
Now a days she still wears some make up and we have fun days doing eachothers makeup. We talk about what looks best. I just try to keep the comunication line very open. Because now the next issue has arrive...boyfriends.
Have a wonderful day. And keep up the good work!