I need to regulate my period

I am 25 years old and I have had irregular periods for about 5 years now. I have been birth control free for 3 years and no pregnancies. And I have been sexually active during the last 3 years. I was with my previous partner for 8 years and had unprotected sex for 4 years and no pregnacies. I am with my now partner and have had unprotected sex for a year and a half and no pregnancies so I know it's me. I have very irregular periods that sometimes are 3 months apart. I never know when I am going to get my period because I will get the symptoms and then *poof* nothing. Right now I am experiencing dull pain in my lower abdomen, extreme fatigue, my nipples hurt beyond belief (which started yesterday) and I almost fainted this morning at work. I took a pregnancy test last night and it was negative. My last period was June 6th. I went to the dr about 3 years ago and had an ultrasound done to see if i had any cysts or anything on my ovaries and nothing showed up. According to them they didn't see anything wrong with me. But yet, no regular periods. Then I was told to go on birth control pills which would regulate my periods. But I don't understand why I would go on BC if I'm already not ovulating? I don't know where to go from here. I am extremely frustrated that I always have to worry about this and spending money on pregnancies tests each month because I don't have my reminder every month. I am at my point in life where a baby would be an ultimate blessing on earth.