Unstable Pregnancy

Hi everyone, i just went for my second ultrasound scan today. It shows growth from 0.76cm (2 weeks ago) and today’s 1.65cm. My gynae has advised to go back 2 weeks later as the embryo should be fully developed by then. Based on my EDD, I’m about 6weeks pregnant. I’m getting a bit worried as based on the ultrasound scans, the gestational sac is small and i didnt see any yolk sac in it. No spotting so far (thank god!) and I’ve been having food cravings every couple of hours. Having badaches at times too. Does anyone has the same problem like me?