I Got On The Depo Shot In 2012 I Was

I got on the Depo shot in 2012 I was due for a shot Oct 31 2013 I didn't go It would have been a year I didn't have a regular period for a year 2015 I started getting periods that lasted maybe 4days my normal period lasts 7 days ad I only had one in March of this year I'm 23 and I'm having the hardest time gettig pregnant