I am 26 year old, And I had sex at the age of 16, at the time I was not aware of what sex is. I was too unconscious, and later I moved to hostel for 7 years I never had sex, but now a days i am having it weekly once or twice without any protection but I nvr get pregnant .and even I never get my period regular .once I had my period after 7 month. What is the reason for that? This time I had period, but no bleeding no pain, just a few black dirty drop of blood?