Advice?

I went in for my first ultrasound on 9/4 at 7 weeks and after a vaginal and abdominal ultrasound, the doctor didn’t see anything in my uterus. My hcg was 218, which I think is around 4 weeks. I am waiting on my test results from 3 days later still. My boobs are still showing increasing symptoms (blue veins and Montgomery’s tubercles). My first positive test was 8/19, is it possible that I am only 4 weeks along and had my dates wrong? Or would a pregnancy not even show up positive on an 8/19 test if it were that early? Doc said there was a slight chance my dates were wrong, but more than likely a miscarriage. She thought she might have seen something in my right ovary so mentioned ectopic. When I did some research it said that if you are earlier than 5 weeks you wouldn’t see anything on an ultrasound but maybe the cyst on the ovary where the egg was released. Is it possible I am still pregnant, or am I grasping at straws?

Anyone experience anything similar or have some advice as to what might be happening?