6 weeks 2 days. Nothing seen on ultrasound

I had my first positive test two weeks ago and it has been progressing nicely. I had my 3+ on clearblue yesterday.

I have had very little symptoms other than tiredness and some cramping. I attended the ultrasound yesterday and nothing was seen on scan. No sac or baby. I don’t feel well and hcg progressing. Should I been worried? I should be seeing something by now. The sonographer wasn’t at all helpful or nice. Is there any hope. This is different to previous miscarriages. I passed them naturally and didn’t progress well. I don’t know what’s going on now.