So opinions/advice please!!

At 19 weeks I got an ultra sound done and the doctor said everything looked great except they couldn't see the blood flow to and from the babies heart very well and she said it was because of the position the baby was in... This is my first pregnancy so I'm freaking out and I just want to know if anyone else went through anything similar!?

I am now 27 weeks and I go in tomorrow for the re do ultrasound and I'm so nervous!!!

Thanks in advance!