So confused!!

I have always been on time with my cycle up until this past month. We have been trying to get pregnant for 8 months and all of a sudden this month my cycle is way off. I was 4 days late my last cycle and I thought I was pregnant but then I started. Now I just finished my fertile window and I am 2 weeks from starting my period and today I had light pink bleeding. All of the things I read said that implantation bleeding only happens 1 week before the next period. Can anyone offer any insight to what is happening!!