I have nexplanon which is a bar that the doctor injects into your arm and stays for 3 years. When I first got it I had a light period for 3 months which is normal but after that when I got my periods they lasted 2 or 3 weeks and were heavy now I'm bearly having one and I've been on the birth control for 2 and a half years now. i don't understand. Anyone else having or have had this problem?