Ultrasounds

When do they normally do ultrasounds? I had one at 6 weeks and 8 weeks because of my previous early losses. I thought I would have one again at 10 week appointment but he only listened for the heartbeat, which is fine, I just really wanted to see that baby! 🙁 I have another appointment at 12 weeks... will they do another or is my next one at 20 weeks??