NT scan issues, baby being stubborn!

So last week I went in because I elected to do the NT scan. After a half hour the ultrasound tech had to give up because she couldn't get what she needed.  I saw the doctor and he said the bay looked great but they didn't get what they needed and to come back in a week. So today I went in again, and after a half hour the tech still couldn't get a good picture!! So I talked to the doctor again and he recommended me to I high risk specialist.  The tech did say it looked fine she just couldn't get proof.  Has anyone else had so many issues? I'm wondering if I should just call it off and not see the specialist, any advice?