Implanon

I had the implanon birth control in my arm for three years, had it taken out in May. We've been having unprotected sex since and I've been following and tracking everything, taking prenatal everyday etc. Were still not pregnant, could this be because of the BC ? Because I thought it'd be out of my system by now! I'm hoping to be positive soon .. Any advice ? All advice or anything is needed and will be greatly appreciated :-)