Must a girl fast Ramadan if she fasted last year because her mother believed she had reached puberty upon seeing a spot of blood, and no other signs of menstruation have appeared since then?

The spot of blood that appeared to this girl is not considered menstruation; rather, it is incidental blood. This is because she did not experience real menstruation for two years afterward, and the discharge of one or two drops of blood is not considered menstruation.

Sheikh Ibn Uthaymeen was asked about a woman who experienced slight spotting of blood that continued throughout the month while she was fasting. He replied that her fast was valid and that "these spots are nothing because they are from the veins."

Therefore, this girl has not menstruated and has not reached puberty, so fasting is not obligatory for her. However, it is preferable to accustom her to fasting as long as she is able to, and if she fasts, her fast is valid and she will be rewarded for it.