I Believe Dreams Have Meaning

I keep having dreams about my sister being put into horrible situations. For example, I had a dream last night we accidentally left her at a store and she got kidnapped. I woke up sweating and crying as I was so scared.
What does it mean? My sister and I do get along(I'm 17 and she's 9) however sometimes we fight.
Would anyone know the meaning as I really want to know.