Okay, well first of all I've seen your pictures, and you're attractive. So get the idea that you're not out of your head
Second... What do you want from girls? Are you looking for a relationship? Are you looking for fun? Like redlemon said, maybe these girls figure youre up for some fun but nothing more.
Girls play the "Lets exchange numbers and I'll call you" game too. You may have just been unlucky and found girls who can't be honest and say "I've had fun but I'm not looking for anything serious."
Maybe you need a different approach with dates. Instead of going home with them right away (nothing wrong with that at all) you could try leaving them wanting more. I heard something on the radio the other day... End the date sooner than you'd like. That way you're both anticipating more.