What Causes Delay In Periods,breast Soreness And Mood Swings?

Hello i been on depo for 5 years. I got on when i was 13 & now im 19. My last spot was april 11th 2014. I suppose to went back july 11th but i never went back. I never had any spotting or period until January and again in February kind of like a period but it was always a week early. My boyfriend and i never use a condom. March i got another period and i think its suppose to come back in 4 days April 4th but my breast have been real sore, i be tired alot & got bad mood swings. I guess my question is can i be pregnant or is is my body getting back to normal??