Yeah, that's the great thing about these early years, there's always another chance to clarify
I've had a moment or two when I've needed to take a deep breath, and have said, "This can be a tricky thing to talk about. People can get shy, but everybody needs to know about this stuff, so I'll try my best not to be shy with you." It's honest and it buys some time to choose the best words.
I read a book years ago that had a great tip:
when a kids asks a question and it's hard to figure out how much information and detail to offer, ask them, "What do you
think about that?" so their answer can give a hint about what aspect interests them and what level they're coming from.
The answer to "Where do babies come from?" might be "from love!" for a tiny kid,
(get back to details later) or... not
from a man peeing in a woman's mouth and her swallowing it, but actually [...]
I try to bring up aspects of puberty, sex, menstruation, and such periodically as they fit into conversation, as if they were as natural topics as anything else around the house. I'm not 100% as casual on everything as I try to sound, but the more I do it, the better it gets. My goal is to have the kids feel like I am willing to speak openly and honestly about anything, anything
under the sun. Tricky stuff!!