I think you need to stop trying so hard.  She's obviously not as invested in the relationship as you are. It  seems like she doesn't respect you and your feelings, and at this point,  I don't think that a plain, heart-to-heart conversation is going to  work. 
I'm going to be blunt and upfront here.  Absence makes the heart grow fonder. As does unpredictability. 
Right now, she's feeling all too assured where she stands with you. And  chances are, your overly accommodating,  emotional and needling  behaviour is probably looking pretty irritating rather than sympathetic.   Her familiarity with your habits and psyche is giving her a firm  ground to stand on and is giving her room to explore her wants and needs  at her leisure, keeping you around as a back-up plan rather than a  first choice. She doesn't take you seriously. You have to change that if  you want to save this relationship, and sadly, that is going to have to  start with your behaviour.
If you call/text/communicate with her every day, stop. If you usually  make an effort to tell her you still love her/express affection, stop.  The best thing to do is suddenly get busy and don't tell her what you're  doing. Go out with your friends. Start a workout regime. Try for a  promotion at work. If you're not a snazzy dresser, start to put a little  more effort into what you're wearing; dress nicely. Take phone-calls  into the next room. Stop checking on her phone and email (you shouldn't  be doing that in the first place).  You need to shift your focus away  from her and let  her  feel a little starved for your attention.  This way, you'll show her that you're not going to wait around forever  until she decides whether or not she wants to be with you or not. And  I'm not saying to do this for "show." I'm saying, really, do this for  you.  
Because if she does drop you one day (I'm not saying this plan is  guaranteed to get her back, but it probably gives you the best chances)  you're going to need something to fall back onto and build your  self-esteem. And this is what this is all about; putting yourself first  and accomplishing something for yourself because you deserve some  you-love much more than she does.
That's about as practical as my advice can get. Good luck.