Im doing the waiting game too! But i got one at 8 to confirm my pregnancy and he said i wont get my next until 23-24 weeks.. im only 15 weeks now.. i need some patience!
Most people don't get any after 20 weeks (unless there's a problem) so consider yourself lucky :-)
I'm due Jan 8th tooooo :)
When i was 33weeks they told me I'll get another one when im 39weeks n right now im 35weeks so i know what u mean