Like myself im 13 days late . I must have not ovulated last month . today I received a positive opk . so im going to ovulate so my period should come in 2 weeks if ice got this right . when you ovulate the lining of your uterus will thicken to implant the (if it happens) fertilized egg . so since that did not happen , that means there was no "lining " to be shed . right ? I think that is why my period is late and I may ovulate soon . still not understanding why my opk turned from stark white just a Bam! Positive . hummm.