Missing Baby in Ultrasound

I’m 8 weeks and 4 days. I had an ultrasound at 5 weeks 5 days and saw the baby but I felt a pop in my uterus so we went to the ER to check if everything was okay but they couldn’t find a fetus or a heart beat but they did before. How can the baby just disappear? Is it possible? Is the ER not doing something right? Has this happened to anyone else? I’m heart broken they told me I’m at an early stage of a miscarriage but I’m not bleeding or cramping. I need some help please. I posted two ultrasound with weeks but I didn’t get an 8 week one. I’m heartbroken someone please help me understand. Has anyone gone through this and still was pregnant?

First Ultrasound at 2 weeks

Second ultrasound at 5 Weeks 5 days