What Is The Treatment For The Delay In The Menstruation?

Hello there



I have not had a period in 4 months i am now lightly spotting and me and my husband have been having sex with out any type of protection. I also was spotting two months ago. i went to my doctor had a pregnancy test done there it came back negative. prior to that i had taken 4 pregnancy tests and out of 4 one was positive. i just need to know what is wrong with me. how am i suppose to get pregnant with my body all mest up?