Worried about ectopic

Long post, please read.

I had my last period on 12th October and ovulated on 24th. I had a positive test on 8th November and ultrasound on same day showed no gestational sac.

My doc had a blood test done on 9th and the HCG level was 562. She said that it is low and told me to repeat ultrasound on 12th to see gestational sac and to rule out ectopic pregnancy.

This is my first time and now I’m worried about this. Please if anyone has any advice or insights into this, please respond. Thanks in advance!