Ultrasound question?

Lindsay
With twins how often are/did you get ultrasounds? Im 17.4 and have only had 1 at like 8 weeks and my last appt they did transvaginal to measure my cervix didnt even look at the babies i seen 1 spine and the top of a head :/ he did do the heartbeats though. But so far everything seems fine how are we supposed to know that they are ok though i should have my anatomy scan in 3-4 weeks but this is stressing me out i had more ultrasounds with my Singleton.