Digital Test at 15 dpo bfn

MA

Hi, looking for advice and thoughts I’ve taken a first response digital early test at 15 dpo and it was negative. I don’t want to believe it is, was really hoping for positive as we’ve been trying for 9 month and had a miscarriage in Jan. Does anyone know if digital test only read higher hcg and if it is possible at 15 dpo for hcg to be lower than test detects?

No signs of pregnancy except no period which I should expect Monday the latest.