Hey girls

I do IVF and on the 15th-9 I had FET #4 (natural)No meds
Ok Beta is on 29th-9 thur fri ans sat I had cramping like AF was coming and spotting (brown)...Then this morning AHHHHHHHHH AF arrived is it possible to still get a BFP ?????
I have 2 children who I had naturally and I had AF for the first 3 months........
Can this happen in IVF

Any help to ease my mind..........

Or is there no hope has this happened to any one then they have got a BFP