Mums aren't the only ones who can talk about facts of life. Don't dads here in the forum talk to their kids about it? My dad, even our grandads, have talked to us a lot about it since we're young!
Monthly period, pains and such, I've learned it from school even before I had it (very rarely I had pains though). And there are plenty of people you can talk about it, like aunts, grandmas, doctors, nurses if you really want to talk to a female about it.