So I’m supossed to be 8 weeks but measuring 6!

I’m so distraught! According to my last missed period I’m supposed to be 8 weeks today. I had been told that my due date was oct. 6 when i first went in but didn’t get my first ultrasound until yesterday thinking I was 8 weeks. While the nurse was doing the ultrasound she wasn’t saying anything so I began to worry and the first thing she asked is if I had any bleeding or cramping. She then finally showed me what she was seeing only my yolk sack measuring at 6 weeks and she “thinks” that is baby next to the uterus wall. Exact words she used. That’s it! I was so concerned and all she said was she would schedule me for another ultrasound in two weeks where you can see more of the baby. I asked about my being off on ovulation or what it could be. I’m sure of my first day of my last period because I wrote it down but I have been reading that can still be off on your baby measuring and can still be a healthy baby. We tried to conceive the following month after getting off birth control and were blessed enough to get pregnant. Could that be a factor. Too many thoughts and worries. Of course I’ve been crying overthinking and reading all these things and worrying that my baby isn’t developing right or their will be no heartbeat since she didn’t see anything yet. I will be scheduling another appointment sooner in a week with another obgyn that won’t only have his nurse practitioner their. I’m hoping my lil peanut🥜 is growing healthy and i get to see a strong heartbeat soon! 😭 Any stories or thoughts welcome🙏🏼