I would like to help you with your question.
First of all, I am sorry this is happening to you. The ups and downs of your girlfriend's behavior is baffling and hard to make sense of.
Have you ever considered couple's counseling? It would seem beneficial for the two of you to be working with a professional to sort out what each of you desires from a committed relationship. Once those desires are understood, then each of you can decide if staying together will allow you to achieve those desires.
As it stands right now, you have done some sorting out on your own about the relationship and want to be together. But she, it appears, is not so convinced about a future with you....that's why she changes her mind from wanting to be with you to then going quiet.
Spending a few days together on a short holiday might also be helpful. If you are away from the daily pressures of life and able to spend time talking, enjoying each other's company and so forth..you might be able to reconnect to what brought the two of you together in the first place. Often the pressures of living cloud our view so that we have a difficult time seeing life for what it really is. She says she loves you. You say you love her. One would think that the love you share is enough to build and sustain a happy and successful partnership. However, life is never that simple and relationships take work.
The reality of life is that you have one and only one life to live. If you believe this is the woman you want to spend your one and only life with...then your path is clear.
I see your are offline right now. When you come online I will be notified and we can chat.