You sound like the nice guy that waits for his chance, and I used to be like that too, we have a similar situation, and I got FZ/Fuck buddy. You should always take your chance, dont let another guy stop you, it may be nasty to steal another dudes girl, but dont hate the player, hate the game.
If she knows to much about you it might be that some of these qualities are not attractive to her and bothers her. Or it is your actions, you're maybe needy or to forward or whatever. Im afraid you can end up in RAW FZ. I've manage to turn the tables around once with this, and I just started to play my role as a man.Everything will go in my paste and not hers this goes with anything. If she calls, if she wants to meet, if she wants to fuck, I do it when I want to do it, I even set a date and time just to play busy. And this attracted the girl that fz me (and attracts other girls too), you can even be rude if you want to, if she likes you she wont be mad at your for it, and you can get away with it easily. It is attractive for a girl to not have full control over a man. But you must give it to her sometimes to keep it stable. If you're in a relationship you have to be a gentleman and share the control in a rate of 50/50
What ever you do, dont be needy, feelings will get you and your mindset mixed up, listen to your feelings but conclude with your mind. Good luck bro!