Period 8 days early??

Jade

I have just unexpectedly got my period 8 days earlier than normal. My cycles are very regular with having been the exact same length the 8 months we have been trying after my miscarrige. Before that they were as well. I am sitting here counting how many days DPO I am and seeing when I can test and now my period has come and I am devastated as it's another month out! just wondering if anyone had any answers as to why this would be happening? I am only 6-7dpo (not an exact) but im 99% sure its not implantation bleeding, I have a lot of cramping and it is quite light and watery at the moment sorry for the TMI. Any answers to what could of bought this on would be appreciated