Scared about miscarriage

Hi all- according to my LMP I Should be 6 weeks and 1 day as of today. However, I went in 6/2 to get my blood work done (beta hcg 99 progesterone 20.9) I went back in on 6/8 to have blood work done again and had an ultrasound done (beta hcg 1175) when they did the ultrasound they couldn’t see anything (no gestational sac/no yolk sac), the doctor said that she thinks its just super early and we couldn’t see anything- I go back this Monday for another scan. This would be my second pregnancy.

Has this happened to any of y’all? What was the outcome? Any info would help . . . I’m worried about a missed miscarriage and or chemical pregnancy.