You're not alone. I had my little boy 20 months ago, and I have just had surgery to correct it. I did try creams etc first but nothing worked. It would tear every time.
One of the doctors told me to have another baby and let it tear again! I asked him if he knew how babies are made, don't know what he was thinking. Anyway, I asked to see someone else and she said this was really my only option. From what I understand the scar tissue is usually what is causing the problem.
I hope you can get it sorted out soon, I know exactly what you're going through!