Nextplanon Implant stops periods?

Hi, I'm new to this app and just saw the option to inquiry to others about birth control. 
So i I'm 18 and I started a new birth control roughly August 17th 2016, and I had one period after having it inserted into my arm and after that I haven't had a single period.
 I'm pretty sure I'm not pregnant as I haven't been growing a belly (although I haven't taken a test), I've been having sex almost regularly with a condom since then and recently we stopped using condoms. 
Has anyone else experienced period loss while on this birth control plan or should I take a test?