Why My Period Is Not Becoming Regular?

hi,, m name is anna,,28 years old, recently married, i had irrigular period quit while, the dr tod me its alright, as i wasn't trying for a baby, i had two missing period fron 19/04/2011 till jully. 01/07 my peiod came but is was brown and small amount it lasted till 12th, frm that time is was on and off all the time, almost i had 3-4day every week, i has internal scan done, the result came as their is ovarian enlargement, the dr gave me norethesterone 2 three time a day, i finished on sunday last week my period didn't yet,,,,,,,,i had hcg blood test last week it was normal so am not pregnant,,, would you plz help e and tell me what to do.
br>sorry about my long question,,,,,,,your answer is important to me.
many thanks