meaning of dreams: darkness

When I was about seven, I had this nightmare:I was in my bed, awake. It must have been around 12:00, because I was the only one not sleeping. I felt the urge to get up, so I walked into the foyer and faced the living room. In front of me was a small black dog, about the size of a large terrier. It was like he was made of a shadow or smoke, and black steam radiated off of his feet. I stood there, staring into his blood red eyes for a second, and he attacked me. He tore at my flesh, and I did nothing to defend myself. He had knocked me to the floor, but somehow I ran away and made it to my parents' bedroom. I jumped into bed right in between them, but amazingly, they stayed asleep. My arms were covered in cuts and long, bleeding gashes. I saw him in the doorway of my parents' bedroom, just staring at me with his red eyes, but he made no move. Somehow, I knew he couldn't attack me around adults. I fell asleep and woke up alone in the middle of the bed. Oh no! I stared at my arms, but there were no cuts and not a sign of blood. I ran into my living room, where I could smell bacon and other yummy treats. My grandparents, who live fairly far away, were there. I asked my grandma if she would come with me, but she asked me to wait for 10 more minutes. Soon, time went by and I took her to my parents' bathroom and the lights were on. Somehow, I knew the monster would be there. I saw his black gasses coming out from under a white shelf, which he was hiding under. I told my grandma to look, but she couldn't see anything. Of course! Adults couldn't see him! I turned to stare at something on the wall, but when I turned back, my grandma was gone. I began to run away, but something told me to investigate the thing on the wall. It was circular and it looked like some sort of Mexican artifact. It had a wolf with an arched back and small pictures on it.The wolf's mouth was open, and I could've sworn it was full of teeth. I took it and ran out of the room as fast as I could, and set the thing on the dining room table triumphantly. I turned to say something to my grandpa, but when I turned back, the thing was a half piece of sausage. Then, I woke up.
As I said before, I had this dream when I was about 7. Ever since then, I've had a very strong fear of darkness and of being alone. I have to sleep with a very bright lamp on, and I still can't even go into a dark room even though I'm 12. I NEVER go into my parents' bathroom either. This was the worst dream I've ever had.