IUD periods

So I have the Mirena IUD and my last period was 2 weeks and ended like January 8-9ish. I couldn't log that it was as long as it was because it wouldn't let me, so the app doesn't even know it was longer. Well <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">Eve</a> said my period should have been last week but because my period was 2 weeks should it not come this week or next week? also me and my SO use condoms and pull-out so that's like triple protection. I have no reason to think my IUD has failed because its in place. I just need y'alls opinion. We're college students so that's why we take all the measures we do. Also my IUD has only been in place for 4 months so its still in the stage of irregular peiods and all. So just give me reassurance girls, I get enough from school alone.