Saw only gestational sac at 5w2d

Kel

I had my first transvaginal ultrasound yesterday. Based on my LMP I would be 7 weeks. I ovulated super late and based on that would have been 5w2d yesterday. We saw only the gestational sac. No yolk sac. My doctor was cautiously optimistic but made me nervous when telling me the possibilities (ie blighted ovum). He said the gestational sac itself looked great - shape etc. wondering if seeing only a gestational sac at 5w2d is normal?!?! Thanks!