You have not mentioned detailed history of your irregular menstrual cycle.
Once in how many days, duration, quantity and quality are important.
Some time what you say as irregular may be normal in our point of view.
The endometrial biopsy
reveals normal menstruating endometrium.
If there is no other cause for irregular periods
, there are tabs to regularize your menstrual cycle.
This tab has to be taken as per advice of the dr. As long as you take this tab child birth is not possible. So once your menstrual cycle gets alright you have to discontinue the tab.