I don't remember my dreams much, but my boyfriend of 2 years now, younger sister who is 16 is always in them, what does that mean?

What kind of dreams are they?

People are usually in your dreams because you've been thinking about them. If they are in your life and they are important to you, your subconscious mind will be thinking about them, and so your dreams will reflect that

I had a horrible dream that my 3 year old little girl got knocked over by a car a died

Horrible dreams I've been thinking about it all day