Ultrasound and second opinion?

They generally do an intrauterine ultrasound around the 8th week to ensure everything is going good internally and they get a better estimated due date rather than just going off the LMP. And then they do an ultrasound at 20 weeks and that is it. I had to have another ultrasound done at 28 weeks because at the 20 week ultrasound, my son wouldn't stay still and they couldn't get the pictures they needed! lol