Hi I Am 27 Years Old I Have Not Had

Hi I am 27 years old I have not had my period for more than 3 months . I had a ectopic pregnancy feb. 14, 2015. I had to have Surgery for removal of tube because it had ruptured. My period came fine but my last period was July 27, 2015. I been have some pain in my ovary so I think feels like my lower stomach and close to my hip, well my question is Why have I miss so many months of period what can it be?