Nexplanon Implant Query

I got the Nexplanon implant on the 18th of May 2015. So I've now had it just over a year. Everything has been fine apart from my period. They have been extremely irregular and I've had some as long as 80 days with little break in between. Over the past few months, they've became about 3 weeks long with about 4/5 weeks breaks. But they're constantly changing which I was told is normal within the first year. I was wondering how other people's periods have been on this form of contraception and whether their periods have done the same and then regulated. Thanks