need to lose the baby weight

Had RNY on 9/10/08 and gave birth to my first child 9/10/2012. I gained 40 lbs while pregnant and since giving birth have lost all but the last 20 lbs.  I would really like to get the rest off.  If anyone has any idea of how to do this please help.  I do get into the gym almost everyday and go for walks with my son after work.  The only difference from pre baby to now is that I have the mirena in for birth control.  Not sure if that is what is making this last 20 so hard to lose. 

I used mirena after my last baby, not sure that is a contributor or not. I am a big fan of paleo/primal eating habits in combination what you are doing with exercise. After my last I still never got off last ten pounds but at the same time the year leading up to this baby I was the healthiest I have been. So with that being said, I would ask urself how heathy you feel and maybe the number on scale doesn't reflect it.

Good luck wish u best! Stacey