Baby measuring small at first ultrasound

Lisa
Hello! Just left my first ultrasound appointment and am extremely concerned. I'm 7 weeks and 2 days, but baby is measuring 6 weeks 5 days. They were able to detect a heartbeat at 127 beats per minute. I have to come back in a week for another scan, which is going to feel like an eternity away. Any similar experiences this early on? Would love to hear both good and bad experiences so I can prepare myself. Thank you! ❤️