Sex and My 9 Year Old

As my daughter gets older there are things that terrify me. Sex being the largest issue at this moment. contributing factors: trauma history, giant desire to be a "good" mother (as in "I will NOT be like my birth mom"), lots of marriage talk, public school 3rd grade in the Fall, friends in the surrogate process, etc etc. She knows how babies are made EXCEPT the sex part. She knows a doctor can help if you have a hard time making a baby or if you are single or a same sex couple. She has expressed here desire to get married and have a baby "lots of them- six girls- and they won't get taken away mommy!" She is probably under exposed to media for her age group, and doesn't see programs or hear songs that are sexual in nature. Except a little frank sinatra. The issue becomes when do I say the sperm get to the egg when.... Right now she would tell you "sperm and eggs get together when you are married". My goal is to be the trusted resource. My fear is that it will be heard and processed as "I can't wait to do that!". For the record, we have a vary open definition of marriage- committed partners. Anybody btdt? She doesn't seem interested in feelings or hormonal instincts....just the hope of being a good mom. Do I wait til she asks the next question? Or preempt the school yard news? How can I help her honor herself, and wait for the maturity to make choices when I know the RAD brain is still so prominent for her?
Sigh. Terror. Is what I feel. Fear that she will see herself as needing to be loved, not left and that she will see a baby as a healing step one day. Why did they stop making chastity belts? That was a brilliant idea. Let's bring it back.