I'd try something like: Babies grow in their mummy's tummy, but not in the place where the food you eat goes. There is a special, safe place inside their mummy where the baby can grow until it's ready to be born. They don't get there by being eaten, they come from an egg which is already inside the mummy's tummy.
I would emphasise and repeat the bits about it not being the place where the food goes, and the baby not being eaten as often as I could, and then answer any other questions she asks.