Implant contraception

On the 28th of November I had my implant taken out. I had it in for just over a year. The 30th of November my period started, and ended 5 days later. I've logged everything on here. And Glow says I should of started this months period on the 28th of December. I still haven't started and it will be a week over due tomorrow. Has anyone had this happen to them or something similar? I took a pregnancy test 3 days ago and it came out negative. And myself & my partner are ttc... Thank you in advance for any advice you can give!