How often should you get ultrasounds?

How often do you get ultrasounds during your pregnancy? This is our first kid and I am 26 and very healthy so I feel like they aren't checking things for me since I don't "seem like a risk". We have had 2 visits so far, 7 weeks (no ultrasound just pee sample) and 10 weeks (ultrasound and pee sample) and everything is fine. Next appointment scheduled for 14 weeks and they said no ultrasound again. Then why am I going? Just to chat? How do they know if anything changed or happened if they don't check on the baby? Am I expecting too much? I just don't know how it's supposed to go but I feel like I think about nothing but seeing my baby again and they said next ultrasound is between 18/20 weeks which is the end of June and feels like ages to check on my baby again.