Ultrasound question

H 🎀 • Athena Mae 06/09/2016 👼 | Married 💕
My last & first appointment was Feb 2nd, I was supposed to be 8w, but only measured 6w2d, due to late ovulation & crazy irregular cycles. The baby has a heart beat, but I didn't get to hear it. We only saw the flickering of it. Well, my doc said the next US is at 18-20w. Well, I go back March 1st, when I'm 10w2d, and I would love to hear the heart beat and see how my baby is progressing, since the 6w scan, as I don't want to wait that long to see how my baby is doing. Can I ask to have an US when I go March 1st?