pregnancy progressing ?

Hi. I'm 8w 5d pregnant. I have no symptoms of being pregnant apart from at 6-7weeks when I had some nausea and then the runs (and my little one had rotavirus just before and leading into that time period so it could have been that not morning sickness). I have a nucheal translucency scan booked for 12w 0d. Here's my worry... What is there to say that my baby (fetus) is still growing and developing? No, I haven't had AF! But, I've heard it is possible to have miscarried but no bleeding. I had a friend who was pregnant with no symptoms (she never had symptoms in any pregnancy apparently) and got to her 12 week scan to find no heartbeat, baby dead probably for weeks. She was just telling me the other day and it freaked me out. I had thought no bleeding meant baby was probably still growing. So, how can I know everything is all right with my fetus? Are there any ways to tell? Aghhhhhhh. Help.