I'm pretty sure I'm living proof that these kinds of methods don't work.
The methods work, however, there is room for user error.
I don't think I know you. Why would you say that? I'm curious!
I'm entirely sure you are living proof that you have done absolutely no research on the topic. That NFP, when properly performed, is as effective as artificial means of birth control has been definitively established for quite some time. Back in the 1970's, what is now called the U.S. Department of Health and Human Services commissioned a study comparing the effectiveness of NFP (when taught by trained instructors and the rules actually followed) with the effectivness of artificial contraception. The result was that, not only was NFP just as effective as artificial means, there were no failures of the method when it was properly applied (that is, no woman who was using the NFP method evaluated in the study got pregnant if she was doing everything as told). Studies since that time have been in agreement with this study.
Here's the citation, in case you decide to educate yourself:
Wade ME, McCarthy P, et al. A random prospective study of the use-effectiveness of two methods of natural family planning. Am J Ob and Gyn. 141:4 (15 Oct 1981) 368-376.
I know for a fact I'm a diaphragm baby. None of these things work 100%.
Aren't you glad for that failure. No contraceptive except sterilization is 100% effective. And even so, after a vasectomy other precautions should be taken until it shown that those determined sperm are being kept back.
PS I am not pro birth control and hold to the Catholic position. But just wanted to point out that all methods have failure rates. Also NFP can be done without harm to the wife or husband. It is not healthful for a woman's body to be pumped with hormones decade after decade. At some point quite frankly the use of condoms must add an element of blaaahh to sex. Not being a guy I am just guessing on that one. So NFP seems the best choice not only for religious reasons but for long term health reasons as well.