Worried

I went to the dr Friday thinking I was about 8 weeks but when the dr did my vaginal ultrasound she said I must be 4-5 weeks. I saw a sac and a light white blob which she said she thinks is baby. She has me coming back in 2 weeks for another ultrasound to look for a heartbeat. I’m so terrified that there won’t be a heartbeat. Has anyone been through this? I need to stay calm but it’s so hard. 😞