Freaking out

Okay so, I found out last Sunday that I was pregnant. On Monday I turned 4 weeks exactly. The following day (Tuesday) I got blood work done by my family doctor and the hcg level was at 87. Okay well fast forward till today (Monday) I go to my OB for my early appointment and pap and he decides to do an ultrasound. I should be 5 weeks exactly today and when he did the ultrasound he told me that he could see nothing. So now I’m freaking out. I have to do repeat blood work tomorrow and Thursday to see how my levels are doing but is this normal to not see anything at exactly 5 weeks?