What is your experience with test strips being faint, but a clear positive on a FR test?

Nelly

So I was able to order some pink dye test ( I’ve been using blue dye tests in my other posts). I bought a FR test and Accumed test strips. I took both test today with FMU, with the FR test you can definitely tell it’s positive, but I’m getting faint lines on the Accumed test strips and the lines do have some color. I’ve had a chemical pregnancy in the past that is why I’m concerned about it. I’ve also been having bad period-like cramps and backaches for the past 3 days, but only at night. I am 3 days on AF, I would think that by now there shouldn’t be any faint lines or I am just stressing myself out? What is your experience with test strips being faint, but a clear positive on a FR test?