Suggest Treatments To Postpone My Periods

I have an contraceptive implant in my arm and also taking Cerezette - I take these to stop my periods however I have been taking these pills since January and have only had 3 weeks off my period. I know it isn't an exact science but I had the implant before it had to be replaced and that worked for over 2 years without any spotting.
I have taken other pills but they have only made it worse - I'm wondering if there is anything else I can do.