7w3d US but measuring 6w6d - help me stay positive!!!

Ok, so this is my first baby and I turn 36 on Sat so I may just be FREAKING OUT! My doc did my US yesterday and wants me to come back in 2 weeks to do another one to check for viability! 😱 Baby had a healthy heart beat (122bps) but was measuring small (only 0.9cm)

and she thought the sac didn’t look like a smooth oval. Also, I had 5 days of light brown spotting, so with those factors combined, she wants to see me back at 9 weeks. I was really really hoping my first OB appt would make me feel better, but now I’m more anxious and nervous than ever! Please send good vibes and help me stay positive!