BFP but low HCG at 15 dpo :(

Claire

Hi all, I got a BFP at 14dpo (took two tests and both clear positives). I got bloods done at 15dpo and was told they're worried - my HCG is only 32 :(

Has anyone had low HCG at 15dpo and gone on to have a successful pregnancy? I had a mc in Oct and I'm afraid I'm going to have another.