Dreams about girls

Lately, I've been on pain killers, and I don't know if they're the cause of this or not, but I'm very, very confused. I've always been unsure of which sex I'm attracted to, but lately I've been having sexual dreams about girls. One was a girl I know and another was one on my favorite TV show. I can't tell if I'm bi or not and it drives me crazy. I do know that I am definitely attracted to guys, though. Is it normal for me to be having dreams like this if I'm straight? Does this mean I'm bisexual? Helpppp :(