I agree, it will be your body adjusting. It's not used to having all these extra hormones going around in it, and so irregular bleeding/spotting is very common.
It can take up to 6 months before it;s regulates and settles.
Your body is probably just adjusting. They should've told you when you got it that, depending on what you're taking, it can take a little while for your period to even out and you may have spotting. Especially if you got Implanon or an IUD.