I got the implanon back in march 2014 and my period has being crazy irregular. E.g had a period that lasted two months my next period lasted 2 weeks the one after lasted 3 days.

I now haven't had my period for about a month and a half and I have had sex since my last period.

I took a test about 2 weeks ago and it was negative.

Is there a possibility I could be pregnant or is my period still being irregular because of the implanon?