Suggest Treatment For Irregular Periods

Hello Doctor, I have not had a normal menstrual cycle since 2012. It sometimes comes and then it disappears for a long time, so like the last time I got my cycle was October 2014 and we are now in march 2015. At first I thought it was due to stress but after a while it just never came back. Took some pregnancy tests and they ve all came back negative. I have also tried taking natural supplements to no avail..... HELP PLEASE!!!