T.K.
Hi A.!
I also reccommend the book and the Billings method (it's not outdated!). There is A LOT more to Family Planning than taking your temperature. There are a lot of other signs. I reccommend practicing the procedures before you jump right into it. And since you're off birth control already, you might want to use other forms of protection until you are 100% comfortable with the Family Planning.
I'm Catholic (went to Catholic gradeschool, high school, and college) and this method got DRILLED into my head. However, I did see high school friends get pregnant because they weren't doing everything correctly. Just do your research and read up on everything. You'll do fine! :)