Hi Curley Sue
I guess they make you wait 7 weeks as they sometimes don't see heartbeats until then. Once the heartbeat is seen they know it is a viable pregnancy. I know it really sucks having to wait. It nearly drove me out of my mind when i had to wait to have my first scan as I was so worried about ectopic.
Try not to worry about lack of symptoms, not everyone has them and they kick in at different times. People still get symptoms with m/c, blighted ovum, so even if you had them it doesn't say a lot really.
If you are really desperate to see whats going on indside you could always book an early scan, they cost about £60 - £100.
Anyway following your pregnancy and hoping it starts to become more enjoyable soon. To be honest, though, once you see the little heartbeat, it will be fine for a week or so then you will worry about the 12 week NT scan, then after that will it make it to 24 weeks and so on. I guess i am saying, that there will be lots of worry ahead, so take it easy and do not google and symptom spot too much.