I don't think God is punishing you for having sex before marriage. That is not how God works. I also highly doubt birth control is playing a role in her lack of sex drive, though I guess it's a possibility. When two healthy people aren't having sex, then it's a symptom of something else. Stress, dissassociation from the relationship, lack of security, lack of emotional intimacy in the relationship...
You need to sit down and talk to your wife, find out what the scoop is. Find out if she is generally disinterested in sex, or if she has no sex drive. I'd suggest your wife to go the doctor, just to confirm that she isn't having a hormonal imbalance of some sort or a nutrient deficiency since health can affect sex drive. When that is sorted out, you two need to start seeing a marriage therapist to help you guys connect where you currently aren't. You might find out it's something simple, like how you two initiate sex doesn't work for you as a couple, or maybe it's something else... Many therapists will tell you that sex is an outward sign of intamacy in a relationship, and lack of sex is a symptom of a relationship lacking intimacy. I bet if you were to examine the relationship, you'd see that there are other things going on in the relationship that need work too, and this is just the most obvious symptom of that problem on your point of view.
As for the debate on if birth control causes abortion... That's a debate best left for another thread. However, by all medical definitions, birth control in any form does not cause abortions. Some birth control does prevent implantation of a fertilized egg, however, the clinical start to pregnancy is not conception, it is implantation, so by preventing implantation, a pregnancy is prevented but an abortion is not preformed. Though I realize and acknowledge that it is the opinion of some that it does, all of science and medicine have weighed in on this issue with a clear consensis that it does not.
http://en.wikipedia.org/wiki/Pregnancy
http://en.wikipedia.org/wiki/The_pill#C ... ion_debate
