1st ultra sound 4 weeks + 1 or 5, is that a sack? Hopefully

Just came back from my first Appointment, she was doing transV ultrasound and found the small dots , about 3mm, and suspect it as gestational sac, but the doctor not clearly sure, but still congrats me . And i have to go back on 11th to take the ultrasound again and see the growth. 
What do you think? Is it a sac? I cant wait to post it when it confirmed by my obgyn..