Weird

I have been trying to conceive for a few months now and I came on my period the other day and I know this sounds pretty normal but I was 5 days earlie! I have been having periods for 14 years now and not once have I ever been earlie so I'm really confused and thought I would see what people say! I'm really heavy so I don't think it's implantation bleeding! Just confused! Advise please xx