Dreams that seem to come true are actually very common. They are known as
precognitive dreams.
Your dreams are probably caused by
1. Your having unconsciously heard or read about the person or thing you dreamed about before or
2. Your not remembering your dreams correctly - your mind rewriting the memory of your dream so that it matches what is happening in waking life.
It would be helpful if you would post about an individual dream(s) and what came true afterwards.
It would also help you to keep a dream diary. Keep a pen and pad by your bed and write down your dreams as soon as you wake up. This way, if a dream seems to come true, you can go back to your dream diary and check if you were remembering the dream correctly.