Stepmom Blues:(

So, I'm a first time step parent and I'm feeling a bit frustrated at the moment.   My DH is a wonderful dad, but sometimes it feels like I'm the third wheel in this life.  I have ALL the responsibilities of a parent but yet NONE of the actual authority.  He will listen to my opinions but becomes offended if I try to suggest and enforce things like making the kids more responsible for themselves... for example, doing their own laundry & keeping their rooms clean.  He will back me up, agree that it is a good idea, but then there is never any follow through.  Mind you they are 12 and 14.  I just keep thinking to myself, it would be very different if they were biologically OUR children.  Then add in the stress of TTC, and a 50-60 hour work week, sometimes I wonder just where I fit in?   Advice from other stepmoms is appreciated.  And go.....