I am in BC and I don't know about the scans I just know that Because I knew my LMP I get on and it is between 2024 weeks, unless there is a reason for needing more. ie. bleeding, cramping, slow heart beat, two heart beats, and complications. But we get one and we have to book ahead at Least 1012 weeks to get an appt. it's just the way it goes here. I don't know how they do the scans they must have another way, I chose to not have any of them done. My personal choice. Medical insurance only covers one ultra sound. You can go to private clinics and pay for additional ones but they too are very full and you have to book way ahead of time.
you're right, in BC you only really get an anatomy scan between 18-20 weeks. You won't get the option for an NT scan unless you are over 35 and/or have a history of DS in your family and you don't get an early u/s unless you have a nice dr who will send you for one OR you have a history or MC, or any other risk.
But you're wrong about medical only covering ONE u/s - they cover them all :) the beauty of living in Canada!!