Possible Implantation bleeding and negative pregnancy test

Hubby and I started TTC this month. Been tracking my period and ovulation cycle via a calendar for months. I have a regular cycle (26-28 days) and never spotted between periods. We are trying for a second kid but this time around I'm so confused. We used the Clear blue ovulation tests and waited until we received a solid smiley face to start trying. I started testing early and it's been negative everyday.

During my first pregnancy I spotted which alerted me to take a pregnancy test and it was positive. This time around I'm spotting today but I've been getting negative pregnancy tests for the past few days. Period is supposed to come on this Wednesday. Has anyone experienced this?