What Causes Missed Periods, Weight Gain, Headache And Discharge From Breast?

i have not had a period since november 2007 i have been tested for pcos thyroid and a few other tests i d like to know whats wrong with me as all results came back normal. I fell pregnant in dec 07 child born in sep 08 breastfed til march 09 implanon inserted nov 09 but still not had a period. other symptoms are: excessive weight gain, headaches, milky discharge from my breast, depressive signs