Hcg question

Has anyone had lower hcg levels and had a successful pregnancy. I also don’t think I’m as far along as my doctor is dating me because I ovulated late... like a few days before I was supposed to get my period late! My doctor says I should be 6 weeks on Wednesday because of my lmp but I think I’m around 4 due to late ovulation. She said my levels are low and thinks I’m going to have a blighted ovum...

Here are my levels.

Feb 25th hcg 49

Feb 27th hcg 91

March 2nd hcg 351