5 days late 17dpo 2bfn no AF

Hannah
As the title says I'm 5 days late, 17 DPO and still no AF have taken 2 hpt one today and one yesterday both negative no sign of AF I'm sure 
My cervix are low and soft anyone else had this and got a BFP in the near future or know of any explanation? I had a 12 day AF this cycle which dr said was hormonal but said it shouldn't affect cycle lengths. I am so confused any help is appreciated