Katie, I don't think you realise that you can't have your cake and eat it too. You seem to think that by getting a guy's number, and going home with another guy you fancy, you're keeping all the options open. You're doing everything but that.
If you decide that you want to be available for something great to happen with someone new, then you have to draw the line and decide that things are over with other people you might have gone out with or fancied: you can't just have sex, let things happen with these guys while still maintaining that hope that you'll meet someone. It's a very stupid attitude.