As you can tell from the many other responses you had, you are not alone by far. I've had two c-sections. After my daughter (who is now 7), I didn't really have any problems during sex. However, after my son, I had a lot of pain. My main problem was a lack of lubrication. But without the lubrication there was no stretching to accommodate my husband which led to the pain.
With my daughter, I breastfed for the first 6 weeks and then had to switch her to formula. With my son (he's 2 1/2), I breastfed (with some supplementation) for two years. I found out at the La Leche League meetings that breastfeeding can increase different hormones in your body which can lead to more problems with lubrication in that area. I believe that may have been a contributing factor to my problems. After I stopped breastfeeding, my natural lubrication started to return.
I recommend that you contact your doctor to make sure that everything is physically as it should be. In the meantime, talk to your partner. A little KY Jelly and a some gentle foreplay to relax and open up that area can really make a difference. I was lucky to have a loving and understanding partner. I hope you are, too.