Week 5 Day 4, gestation sac without yolk sac?

Hi! This is my first pregnancy, we’ve been trying for 2 years. Just had my scan today at 5 weeks 4 days and my doctor cant seem to find baby nor yolk sac. She could only see the gestational sac. Will be coming back again in 2 weeks for another scan but I am very worried that this pregnancy won’t be viable. Is this normal? #pleasehelp #PCOS