I have boys so it's a little different, but the similarity is that they are all changing. I tell my boys that their body will do some pretty interesting things in the next few years as it practices to become an adult. My older son so far hasn't freaked out about anything personal happening to him because he's been told it's all par for the course. And I always tell him that I know WAY more than the kids at school and that if he hears something he should ask me to make sure it's true because most of what they say at school (middle school for sure) is not necessarily true. I also always emphasize that he has no control over what his body does, what his 'parts' do, when they do it, how often (or not), how big, or how much hair or anything of the like (as kids/teens have a tendency to compare themselves to each other and point out who is lacking in which department, if you follow me.)
A cute thing happened a couple years ago, my younger son who was 6 came running out and said that my older son, who was 10 at the time "Has HAIR down there!!!", so excited, wildly pointing toward him! I was just as excited and said "I know, it's it great! He's turning into a MAN!"..."And you will too someday!!". It's really neat to be a mom and watch them growing.
All the best!

Her school may have a day coming up to teach preteens about this stuff. I think our elementary school offers it in 6th grade, and it's after school, parents have to sign a permission slip, stuff like that. It helped my son...and in order to make sure he understand he needs to talk to us about any issues and he can, we told him if he can't ask us questions due to embarrassment, we told him he can write it down and leave us a note and we will write back to him, privately OR we told him to call his favorite Uncle and ask questions, but know, his Uncle will be telling us about the conversation for safety. We try to realize it's a touchy subject...embarrassing really for them, and give him lots of options to keep open communication - but we are also trying to enstill that these issues are important to be educated about and we want him informed...Good luck!

im in the same boat mine in 10 in may and mood swings have already started have got her on evening primrose which seems to have helped a bit but my girl is embarrassed about it too and i have always been very open too i guess if their peers are embarrased they take their que from them rather than us i have also got books from the library for her to look at she didnt want to look at them with me but i will try again soon
hope this helps

Well, she is being very moody and emotional. She isn't developing physically in any way, just moody and it's really starting to try my patience. UHG, how do parents survive teenagers???