Nexplanon birth control

So this is my second time around with nexplanon. my current one was placed back in March or April of this year. my periods have always been irregular and sometimes I have multiple a month.. I know it's possible for BC to stop your periods completely but up until now I have never gone a month without a period.. my boyfriend of 5 years and I haven't used protection since 2014 when I got my last nexplanon inserted but now I'm a little nervous since it's the end of September and no sign of aunt flow! could I be pregnant or does this seem like maybe my periods have stopped???