You think you're ready because you're 15. Believe it or not, 10 or 15 years from now what you will know is that at 15 you were not ready.
Dreams don't mean anything but how your brain is interpreting what is happening in life right now. Sit down and talk to your boyfriend.
Sounds like the plot to the movie Scream. All along her boyfriend was the killer. But if it makes you feel better it was just a dream.