So I'm 17 now, and I've had MD since I was 11. I knew that there was already something wrong with me when I first started daydreaming UNUSUALLY. I think what first triggered my MD is a chinese movie called So Close, I was so taken by this that I started making a male character to correspond to the female character in real life(but of they're not real, except the actress). I was dribbling a ball, and the plot was they're both actors in reality and they're together, I remember my mom even caught me 'lipping' what they were saying in my head and I told her i'm just singing.
After several years, this fictional male character has evolved. I'm sorry, I can't disclose more because i'm feeling a little uneasy sharing this to strangers I've never talked about this to anyone at all. Maybe some time again.