My u/s report says in a gestational sac is a yolk sac without embryo yet, but doctor comments it could be myoma. gs is 1.2cm. could yolk sac be myoma?

Unlikely: Myomas, also known as fibroids, are rarely cystic. They can degenerate and contain fluid, but are unlikely to look like a gestational sac. You likely need a follow up ultrasound in about 2 weeks and correlation with beta hCG levels (blood test). Your gynecologist, however, can make a specific recommendation based on your history and physical exam or lab tests.