Lately my period has been irregular (comes every other month)

But the months that it does come I spot days prior to the due date and then it will come as normal on the days that I’m supposed to have it. But this month I started spotting 1 week+ before the due date and now that the due date is here, my cycle is extremely lighter than usual.

No i am not pregnant, No i am not on birth control. does this happen to ANYONE else?