HI I Have My Implanon Done Last Year In OCT,2015

HI I have my implanon done last year in OCT,2015 and after that there was a delay in my periods for 10 -15 days. And after that it was regular. However, from last 4 months there is no sign of periods. I have consulted the Doc and done pregnancy check and its all clear( not pregnant). Only one of my harmone level is high. Do you think there is anything dangerous or serious because there is so much delay in my periods.