Why Hasn’t My Period Started 7 Days Past The E Date Along With Mild Lower Back Pain Post Unprotected Withdrawal Sex?

Hi, am 7 days late from my period, I had all the signs that my period is coming but up to now nothing. I knew that the following day my period would come so I had unprotected sex using the withdrawal method, am just wondering why my period is not coming right now I just feel lower back mild pain