I'm 11days late with a negative urine test result i noticed a blood stain a week before my periods were due. if i'm not pregnant what could it be?

Possible pregnancy: Although home urine tests are very sensitive, you may want to repeat the test. The bleeding you experienced could be what's called "implantation bleeding", that sometimes happens when a fertilized egg first implants in you uterus. It can be misleading because some women think the bleeding is from their period and don't realize they are pregnant.