Small gestational sac ?

Went in for my first ultrasound at 7w6d. Baby’s heart rate was 161 and measured on track.

OB phoned today to tell me my gestational sac is small and wants me to go back for another ultrasound in 2 weeks, when I’m 10 weeks pregnant.

Everything I’ve read online is negative and scary. I’ve already had 3 losses this year and am really scared of another.

Has this happened to anyone else?