Any help is much appreciated!

I went for a ultrasound 2 weeks ago and discovered I was pregnant. They told me I was about 5 or 5 1/2 weeks along. I had to go back today to see if everything was developing and the only thing that developed is a yolk sac. I was told I was about 6 or 6 1/2 weeks along this time. There was no heartbeat or baby that could be seen. They told me to cling to the hope that I developed a yolk sac. I go back in 2 weeks to hopefully see more. Has anyone else had an experience like this? I'm so heartbroken 😞