Are BFPs consistant

Question… I have had a miscarriage and a chemical this year & both were identified around 8/9 dpo… does this mean I will always be able to identify early? Or is each cycle different?

For context, my cycle is clockwork 28 days and I ovulate in line with the app from the ovulation tests I have done.

I am 8 DPO today & I was getting some cramping the past couple of days and have been a little tired (but it could just be the big weekend I had) but in the past it’s usually my boobs that give it away… but this morning was a BFN anyone have any advice?