[LittleMiss]

I'm sorry but you're okay with having pre-marital sex but not to use contraception?
That's a double standard if I've ever seen one.

In Catholicism, preventing conception is the sin, not taking contraception (people often forget this). By using the pulling out method, you're attempting to prevent conception and thus, making the same sin. Using the rhythm method is acceptable because you're not actually having sex and preventing conception at the time of the act. However, I still don't recommend this method as a way of preventing pregnancy.

You can also become pregnant when pulling out, pre-cum can contain sperm.

I don't think you can pick and choose, um and ah about this. It's not fair to say "I don't want to sin and use contraception but I'm okay with having sex."
It's not fair on your partner as I'm sure he doesn't want to contract/give you a disease or to be a father.

By the way, the pope has lifted the ban on condoms as he believes that limiting the spread of disease is important (I know this was only for homosexual contact but if you're going to bend the rules, you may as well bend this one too.)