Irregular period cycle. If the stress.

Everyone has stress. If you have irregular cycles since 12, and you feel it's due to stress, it may be. But the most common reason for periods to be irregular between menarche ( start of menses ) to 21 years is irregular flow of hormones. You are unnecessarily ascribing it to stress. When menses start in a woman, it is due to complex interplay between hormones. and it suggests maturing of the reproductive organs. This hormones released are erratic at first and slowly they stabilise to form a repetitive regular pattern. Hence adolescent girls who have irregular menses are counseled to just wait for these irregular hormones to become regular on their own. Some may have other reasons for irregularity like thyroid disorders, anemia, ovarian cysts etc. these are ruled out when these girls seek medical attention. The only need for treating irregular cycles comes when patient has excessive bleeding lasting more than 5 days.

If stress is a very important factor you can seek help of psychiatrist or psychologist to learn techniques to cope with it. These may help. Many patients with irregular cycles and stress also tend to be obese or very thin/.....This too can affect the hormones and cause more delay