5 days late / only negatives

Has anyone had experience missing their period (possibly due to stress ...hopefully not stress) and multiple negative tests up to 5 days after missed period?  I also experienced cramps at time when I was supposed to have my period and a few days thereafter. Still negative tests but no period and no faint positive lines. I've been regular for the past 5 months. Then December came along. Did I feel implantation cramps?  Can you please share your implantation stories and how many days you felt it past ovulation?  If the cramps I experienced were implantation it was most certainly 12 dpo.