You really don't know til you see the scan , would you like twins ? I would but i think it would be a nightmare lol my DH has twin brothers who were 6 when we met but are 20 in a couple weeks they were great when they were younger so mischievous. Just think with Dylan and twin boys i would go mental i need i girl! lol.
I am confused about your scan cause if its 7 week since your ET you would be nearly 9 weeks pregnant. They can get a HB from 6 weeks i would price up a private , my clinic charge £130 but i just found somewhere else charging £85 whereabouts are you peartree?