How late did you get a BFP? (After previous BFN)

Ashley
I am TTC#2 and going crazy. I am 16dpo on CD35. I've been testing for the past week and all negative. I have a clockwork cycle but still no period. I found out at 8dpo with my son. 
Has anyone not gotten a positive test until well after AF was due? I'm crossing everything that it's not just my cycle playing tricks.