If you're showing, I would say that the 2nd trimester/12 week rule goes out the window. You're only a few days away from the 12-week magic date anyway...go ahead and tell your family now and then spread the word! You might be surprised by how many people haven't noticed LOL - I didn't tell about my 2nd until I was 22 weeks, my 3rd was announced at 17 weeks and I made it 12 weeks with my twin pregnancy and very few people suspected before we shared the news.
Congrats and share your news!
To those who don't understand keeping things under wraps...miscarriages are most likely to happen in the first trimester. Many women keep things under wraps first trimester so that if something awful happens, they don't have to tell the whole world and risk having people who didn't hear about the loss ask "how are you feeling, how's the baby?" weeks or months after a pregnancy loss. We didn't tell anyone until we were reasonably sure that we were carrying a healthy baby.