If you have a bfn at 12dpo your out right

I see most people get a vvfl atleast on there tests from 10dpo so if I got a negative at 12dpo I'm likely out right. Today I'm getting a crampy feeling. Mild and my boobs are still really really sore and huge. I've had loose stools all week. Hsg was 3weeks ago. I really thought I had a chance.