IUD spotting or period?

How do I know if it’s a period or spotting lol! Idk how many underwear I ruined now over these last few weeks😭 I had my mirena IUD put in February 25th.

Today im crampy, moody, headaches for 2 days, spotting more but not enough for pads. I can still have sex & stuff 😅

When did your first period come after having your IUD put in? Was it lighter or heavier?