Did I reach puberty by practicing the bad habit before having a wet dream, or only by having a wet dream, and do I have to make up for missed prayers and fasting?

Masturbation is forbidden, and one must repent from it. The fluid is a sign of puberty. If puberty was confirmed before nocturnal emission, there is a difference of opinion regarding making up prayers that were performed without ghusl. You may adopt the view that making up prayers is not obligatory for someone who was ignorant of the condition. As for fasting, there is no need to make it up, because purity from janabah is not a condition for its validity, unless you broke your fast believing you had not reached puberty, in which case you must make it up.