Just out of curiosity what is natural family planning?
There is a higher chance of getting pregnant if you have sex around your ovulation date. Natural family planning focuses in tracking your cycle, temperatures, etc. Have you taken a course on this?
If you haven't taken a course on that or extensively studied up on it and are scared about getting pregnant, you really shouldn't have gone off birth control pills.
I got pregnant doing the natural family planning. I had an egg release a week early.
What method of natural family planning are you using? There are signs leading up to ovulation. My husband and I use the Creighton method and it has been amazing. If you know for sure you had sex the day before you ovulated then there is a good chance you will be pregnant.