9 weeks ultrasound

I’m 9weeks and 6days today and I went in for my intake appointment. They tried finding the heart beat with the Doppler but couldn’t. Then they used the ultrasound machine on my stomach to see the heart beat. The doctor said she’s worried and that she would’ve wanted to see more on the screen and scheduled me for an internal ultrasound tomorrow morning. I was under the impression that I’m too early in my pregnancy to see anything in am ultrasound when doing it on my stomach and that I had to get one done internally. Last week I saw the heart beat on the screen but this week they couldn’t tell if the heart was moving or if it was the screen moving. The doctor told me I either got the dates of my last period mixed up and I’m not as far along as we think, or the baby was curled up so she couldn’t see anything, or it’s not a viable pregnancy. I can’t stop worrying and I’m so scared as this is my first pregnancy. I haven’t had any severe cramping or bleeding. I’m worried

UPDATE: everything is fine! They got my due date wrong. I’m actually 8 weeks and 5 days, they originally thought I was supposed to be 10 weeks today. I’m switching doctors, my doctor didn’t even think to do an internal ultrasound from the start and she immediately went to worst case scenario and made me panic and nervous. Last night was the longest night of my life. Thank god everything is okay