TTC but confused

Hi, my partner and myself have been trying to conceive for 2 months (1 month properly). Since I came off BC 6 months ago I've had AF every 28 days with no issues at all however this month AF arrived 4 days earlier then expected after experiencing the usual pregnancy identifiers however AF has been heavy so don't believe this is implantation bleed. Anyone have any ideas or suggestions that may have caused this? I've not been stressed, have lost my appetite and not had as many cramps that I usually get during AF . Thanks in advance