Ultrasound

I am 19w6d pregnant and just had that 1 hr ultrasound where they check all of baby's areas and organs, but my baby was scrunched up in a ball and doesn't change positions for doctor to check the angles of the heart, what can I do to help her switch around? If I have to go in again it'll be my 3rd time.. and it's just making me nervous, making me think something is wrong...