implanon

I'm a tad confused I've had the rod/implanon in for about 1 year now but anytime my period doesn't come when it's meant to I get stressed out I have been told that the Rod changes with your period around but I'm just abit confused how long can your period not come for when you have an implanon ?? I'm 20 days late can anyone help me please just so I know from a another girls point of view please it would be most appreciated 😊