Advice needed :(

Today I’m suppose to be 6 weeks 4 days, I went in for my dating scan due to irregular periods. They could not see a gestational sac. She said my endometrium lining was thick, which she said is a good sign, but has this happened to anyone else and had a success pregnancy? I’m so worried :(

I looked online and I’ve seen the term “pregnancy of unknown location” used to describe it. Has anyone had this? Any advice please.