What Causes Irregularities In Periods?

I'm 33 yr old married woman. I'm obese & suffering frm Hypothyroidism as well as PCOS since 2001. The gynae I consulted then prescribed me Ovral-G for atleast 6 mths. & then discontinue the drug & see whether I'm having normal periods since my onset of periods I had some amount of irregualrity. The doctor told me that it will be ok once I conceive.But my periods never became regular, sometimes it used to be & most of the time not. I got married in 2009 & ws still continuing wth the contraceptive pill (ovral-G) since we dint want a baby at that time.i last had my periods on the 19th of August, 2010. I got a pregnancy testy done also, but it came negative.But now we wish to have a baby but I feel scared to see a doctor. Please help me & I want to live.