Kinda panicking a little help.

So yesterday I was in the er for light spotting and the reason I went was because I’m RH- so I needed the shot. They checked my HCG and it has has been steadily more than doubling every 48 hours. But on the ultrasound they found a very very small hematoma and my gestational sac but no yolk sac yet. I was 5 weeks 2 days measuring 5 weeks 3 days. My question is should I be concerned about not having a yolk sac yet. I’m nervous I’ve had 2 previous losses.