Also some people get pg right away other 3-4 months some even longer everyone is different. Mine came back right away.
I had the same thing. And had mine about the same amount of time. Mine was my period. If it was around the time you normally got your pd then most likely is. If it was just spotting for a day or two, id wouldnt say it was your period just withdrawl bleeding. The best thing you could do it just track it, because since you said you never had periods it would be hard to tell. I had very light/ spotting periods on mirena. You could also tell if you ever had cramping the time your pd should of been here, you still have those symptoms even if you are not bleeding.
Hope this helps goodluck!