Congratulations on talking to your parents, it sounds like you're doing a wonderful job of fitting your feminine side into your life.
I've been following the parenting thread you started recently (as I posted there we've a girl of 7 and a boy of 1&3/4, and it made me think about just this issue. I think it is best not to hide this from your children, but telling the broader family is daunting. Well my SO's parents, really, they are lovely people but I really don't know how they would react and of course, as with my SO, while they may well be openminded generally it maybe difficult for that to extend to a son-in-law. I think my parents would be fine, I think I would have come out to them already if I'd realised what it was I had to come out about before I met my SO.
Good luck with the next steps, I'm sure as your SO is so supportive telling her parents will be fine too, after all they brought your supportive SO up! You are providing a wonderful example of how an identity like ours can be included into family life, and not kept hidden away.
I am not out to anyone and I can only hope that I can follow your example in the not too distant future.
Love
Ivie