I had my baby September 2015 and got the Implanon in my arm for birth control in October. I have…

I had my baby September 2015 and got the Implanon in my arm for birth control in October. I have been getting my period every month nothing heavy kind of light. but this month I haven't gotten anything and I am more than a week late..I took a test which was negative, is that normal to not get them? Also if any of you have tried this BC share your experiences with it please! Ty