What Causes Delayed Period And Mood Swings?

hi i was wondering about my situation right now as of me having an uid Mirena since last April my period has been every 2 weeks since up until december but now since dec 18th my first day of my last period i havent had any period yet.... i have also been having mood swings and gettin emotional.. ive had sex my last period also and was wondering if its possible that i can be pregnant... i feel like i am...