If you went on mirena before getting your period back, did your period ever come back? if so, when?

I got mirena inserted at 15 weeks PP. My period had not returned. 4 weeks later, I had what I thought was a period. Then nothing for the next 3 months. Now I just started bleeding again. Could that be a period? Something else? I'm 8 months PP now, and still nursing the same as always.