ANDY'S ANSWER: I would not be concerned because you are well within the norms of puberty. You've already had one period, so officially you have already started menstruating. Some girls will have the first period and then not get another one for 6 months. It can take years for you to become regular and some girls are never really regular even after they become adults. You have all the signs that your body is going to have another period soon. Carry a pad with you at all times so you don't get caught by surprise, and feel free to name your first child (in 10 years) after me.