High HCG 5wks 2 Days Only Sac Seen

This afternoon I had some brown discharge in combination with lightheadedness and was just feeling off so went to ER because of prior miscarriage. My levels were 28000 but when I had the ultrasound only the sac was seen. The doctor said everything looked good and the sac was normal and measured right. With my HCG being that high would they see more than a sac? Ultrasound tech said they don’t normally see anything that early and also asked me if I was on hormones. Thought it was an odd question.