Should i give up hope this month??

I am currently CD 31 and 6 days late. My AF was supposed to show Friday and didnt come. I have never been this late before. My periods are around cd 24-26. I have been having mild backaches and have had cramping in my lower abdomin on and off. I have taken 4 tests and all are negative. Has anyone ever experinced this and ended up with a bfp? Can anyone give me tips or info. I dont really have anyone i can talk to about this so i need all the help i can get.