How can one make up for days not fasted or fasted in Ramadan without a firm intention, after coming to know that puberty is not limited to menstruation?

There are signs of puberty, upon reaching which a person becomes religiously accountable. They are then obligated to fast Ramadan with a firm and pre-dawn intention from the night before Fajr. If the intention is hesitant or made after Fajr, the fast is invalid, and the days fasted with such an intention must be made up. Ignorance does not waive the requirement to make up these days.