Having irregular menstrual cycles where they occur every 2 months and last 3-4 days with very little bleeding is not necessarily something to be worried about. Some women naturally have less frequent periods without it indicating any health issues. However, intense physical training can indeed disrupt the menstrual cycle, especially in women with low body weight. If you have concerns about your menstrual cycle, it's always a good idea to consult with a healthcare provider for personalized advice and guidance.