im worried about weird sexual behavior going on with my litt

So i need good parenting advice .
Last week my sisters friend had a sleepover with her and my mom told me how she accidentally peeked on them and saw them both on top of each other making out-girl on girl. She then felt very uncomfortable and didn't let them sleep on the same bed when they went to sleep. So lately every time i walk out of our room ( me & my little sis) and walk back in i have noticed that shes always lying on her stomach as if shes been humping the bed and her face looks all weird as if she just woke up meanwhile i knew she wasn't sleeping and then she acts very weird and quiet when i ask her wats wrong and if shes tired. I know shes doing something sexual and its really worrying me bc i used to do this when i was young as well and know that its wrong bc then your most likely to have sex at a earlier age... How should i talk to my little sis if next time i catch her ? she already hates it when people tell her wats wrong and right and i don't want stuff to feel awkward nor do i wanna think of her differently but i am sooo worried please help

I think she is just being a 9 yr old girl. Just like a 9 yr old boy. It doesn't mean that she will have sex at an earlier age either. It just means that she is having feelings of sexuality. It's ok. Don't panic. It's totally normal. You said you did it too. Did you have sex earlier. I didn't. It's ok. If you want to talk to her just tell her that it's ok and you sorta know what she is doing, but to be careful about her choices later when it comes to boys and really having sex. Just talk to her without being bossy.

mom to 2 boys

I would just let her do it. She'll grow out of it. Talk to her and ask her why she is doing it. If she won't answer, don't ask her again. She'll stop eventually.

She's nine?! Jesus Christ! She's too young to be making out with anyone! Who gives a crap about how she feels when people tell her what's right and wrong! Knock some sense into her!