Confused!!

My body is normally like a clock, always get AF bang on 28 days at normally the same time of day! Had my copper coil removed last month and had sex during my fertile window in March. AF is now 5 days late but I'm still getting bfn's (I've done loads!) it's really frustrating not knowing what's going on. Would i still be getting a bfn this late after my period if I was pregnant? (Trying for #3 and fell for my others within only one cycle so don't really have any experience with ttc if that makes sense!)