Ah yes...the famous inequity of sexual desire between partners. I have been married for 17 years now and for the first 10 years my situation was like yours. My wife was raised in a strict religous environment where they did not even speak about it. When we got together it was very awkward. But it started changing when we decided to have children. She was starting to enter her prime around 28 and I was 30. So we decided to head up to a very romantic B&B in the Arkansas Hills and spend all weekend in bed.
Anyway...after we had the first child her body started to change...we started talking about our fantasies together...and each year it gets better and better. BUT, having a child is not the answer...the answer is that we are products of our environment sometimes. This may be part of the puzzle. The other part may be that she really has no desire at all. Some women I have met don't have a physical desire sometimes...sometimes it takes alot of foreplay to stimulate a need for sex. The one thing that has always worked for me is several weeks of cuddling and just closeness. It creates some type of warmth and comfort.
I hope you can be patient with her, Lord knows that my wife and I had some real catfights over this. But now we seem to be on the same level in our desires. Hang in there and work with her. Love her and talk to her.
Good luck.