The only way I can fully explain my personal growth and interest in religion to people is by first saying that I did not grow up with much religious knowledge and admitting to the shortcomings of my mother. My mother is okay with me telling people that, so is it still considered backbiting my mother by revealing a fault of hers even though she is fine with me doing so?
If saying such things entails that your parents are not religious while they appear religious, then it is considered backbiting regardless of whether your parents are okay with saying that or not. The criteria for backbiting is revealing hidden faults of a believer in their absence whether they are okay with it or not. It is better to avoid those details about growing up in a non-religious environment. Instead, you can say that after growing up you started to have more interest in religious education.