Ah now, here's my story to add to the mix. DH and I were trying for a baby. Our first son was born too soon and didn't make it and we were obviously grieving and hoping all intermixed. One Sunday morning, I was sitting in church with DH on my right hand side. There was nobody to my left. And then all of a sudden I could feel a presence there. A substantial, warm, comforting presence. The feeling was so strong I actually remember laying my head sideways, away from DH, as if to lay it on the shoulder of the 'person' sitting next to me and I could feel an arm around me. And at the same time I could hear a voice, a man's voice, saying, "There's a little boy waiting."
I must have been three weeks at the time, way before you could test that early, and didn't find out for another ten days.
To this day I don't know whether the 'little boy' is the one we lost, Christian David, or our new baby boy who needed to wait another 38 weeks to be born and turn into the wonderful young man he is now. Having got the child I now call, erroneously, DS1 here with me, I'm sort of hoping the one waiting is Christian and that one day we'll be together.
Enough. Babies are all a miracle. And despite your protestations Dondon, I hope you do get those twins. Each child brings a blessing. 
The final twist to the story is that Christian actually had a twin who I lost at only 7 weeks. I'll never know for sure, but I think she was a little girl. No messages about her though!