Abnormal Periods, Dull Aches Around Ovaries, Pregnancy Test Negative. Problem?

I am 25 have had abnormal periods my whole life. I have been having a dull ache that comes and goes around left ovary . I had a negative pregnancy test . But have been moody and sometimes a little more emotional than normal. What is wrong w me? Did I test too soon or might I have cysts on that ovary. I have known to have cysts on the right side but was in a lot more of a pain as opposed to a dull annoying ache