I read your post and I have 2 theories. #1...She might be stringing you along, not in a mean way, until she finds someone else. Right now you fulfill all her needs emotionally and physically but without the commitment. In her mind she still free to search since she's single. You're a safe alternative.
I was in a relationship just like this. We spent damn near 24/7 together. I even went home to meet her family in another state. After about 7 months I finally told her how I felt and her response was like hers, I love you but just not that way I hope we can still be friends, well after a few months we started to drift after she started dating another guy. It hurt and I moved on but always had feelings for her. What I didn't notice until later was that while I spent all this effort on a girl who didn't feel the same I missed out on someone who did. I spent so much time and energy I missed the one who did want me. You're focused so much on her you are missing opportunities with someone else who will give you what you want. Distance yourself and move on. If it's meant to be she'll come to you. If not you'll be able to find someone else who wants you.