Does one incur sin for abandoning prayer for a period due to a mistaken understanding of the signs of puberty, and is that considered disbelief or ignorance?

The growth of coarse hair around the pubic area is a sign of puberty for both males and females. If you intentionally abandoned prayer after reaching puberty, there is a difference of opinion regarding the obligation to make up for those prayers. If you thought you had not reached puberty, but then became certain that you had abandoned prayers while you were, in fact, an adult, then you must make up for them according to the majority of scholars, though there is a difference of opinion on this. There is no sin upon you if you were ignorant of the ruling, but making up the prayers is obligatory according to the majority of scholars.