Ergh! 16po and 4 days late

I know I’m only 4 days late but I’m usually on time, I’m having the worst cramps, my back kills and ribs! My nipples hurt and I’m on and off nauseous. I had a BFN this morning.

How long could it take for a BFP?

I just want to know if it’s AF or something else 🤞🏼