Someone told me that the fluctuations in my menstrual cycle is because there is no ovulation.i haven't missed my menstruation in any month.is it true ?

Track timing: The way to track your cycle length is from the first day of one period to the first day of the next. A normal cycle where a woman ovulates may be anywhere from 21 to 42 days apart. Not all ovulating women have a period exactly every 28 to 31 days. Many women may have a period every three to five weeks, ovulate every cycle, and therefore have one period a month but never at the exact same time!