Gestational sac

I first received a Bfp Nov 13th. I called my OB that day and they wanted me to come in today (nov 22nd) for an ultrasound. Based off my last period Sept 27th, today I would be 8 weeks but since I had just gotten a positive until Nov 13th I figured that wasn't possible. Anyways I went in today and all they could see was a gestational sac. They sent me for bloodwork which I was supposed to hear back on before the end of the day and didn't 😔. Has this happened to anyone? I'm assuming I'm just really early but I'm panicking. Here is a test from this evening so clearly positive. Just want someone to ease my mind.