AF is 7 days late but still BFN

[Cb26]

So I was due AF on the 16/17th so far nothing. I used a clear blue digi and I got a bfn. I checked my cervix and it's so high up I could hardly reach it. No real symptoms the odd painful twinge or stabbing pain in my boobs but that's it.

Can I really be pregnant at 21dpo?

Normally my periods are clockwork, I haven't recently finished any bc or started any medication. Just feeling hopeless.