If you are pro-life, what kind of birth control do you use?

I'm strongly pro-life and I believe life begins with conception...when I study different methods of birth control like a regular hormone pill, I worry that I will have breakthrough ovulation and the only reason I won't get pregnant is because the lining of my uterus is so thin (causing no implantation of the fertilized egg). I know many people who are anti-birth control. We have been using condoms for about a year and a half but I don't want children for another 4 years or so. What do other people do?