I had a early scan today!

Since before I got my BFP and since I found out, I have had really bad cramping which I know can be normal but due to being a high risk pregnancy and it making me feel physically sick today I called early pregnancy services near me and they advised me to come in for a scan! I measured at 5 weeks and I couldn’t see anything but the sac which measured at 8mm so they have asked me to go back again on Thursday for a second scan. Does everything look normal as I thought I would be seing a yolk sac at 5 weeks?