When could you see your baby?

I went for an ultrasound and what I believe to be 6 weeks and 2 days. My Gestational sac is measuring 5weeks 4days so I must be behind. They did a transvaginal ultra sound and only saw my gestational sac and nothing nothing else. I also don’t have any real symptoms anymore. Would this mean I’m 5 weeks and 4 days of the 6 weeks and 2 days? Should i be worried?