Fertility awareness (natural family planning) is not a contraceptive choice for the faint-hearted.
This isn’t because the method is difficult or ineffective. You need to know what you’re doing, and you need to be able to handle your fertile time, but it’s not rocket science.
The hardest part is probably telling your doctor (and your friends) that you’re relying on it to avoid pregnancy.
I’ve heard reports of eye-rolling and angry sighs from some doctors, or more dramatically “Well, don’t come back to me if you need an abortion”. [Not all doctors are like this, mine was lovely]