HCG & Ultrasound, question.

On Tuesday I experienced cramping, and went to the er. They did a beta hcg, pelvic exam, urine & ultrasound. My hcg was 865, pelvic exam showed that my cervix was closed, urine was fine, & the ultrasound pretty much showed nothing. I was expecting to be about 6weeks2days based on my last menstual period, but because my hcg was 865, they said that I am most likely earlier than that. They also told me that it was normal to not see anything on ultrasound with hcg under 1000. They did report a very tiny fluid in the left side of my uterus, but could not confirm that it was the pregnancy at this point, and had me follow up with my obgyn Thursday for another beta hcg to make sure my levels rose accordingly & to discuss another ultrasound to locate my baby, and rule out an ectopic pregnancy. My hcg on Thursday was 2006, which is great, it doubled & then some, which is exactly what it was supposed to do, and my obgyn had me follow up with another ultrasound this morning. At my ultrasound this morning, again, baby could not be located, although the tech did say she thought she could see the tiny spec the er noted three days prior. I'm just confused because if my hcg was 2006 yesterday, it should be about 3000 or so today, and I was told you can generally start to see things around 1000. Has anyone had anything like this happen? I'm trying to stay calm, but I just want to know everything is okay. Praying my ovulation was later than expected and baby is just too tiny to see. I'm almost certain another ultrasound will be done next week, but it's going to feel like a lifetime until then.