Realtionship problem :(?

I have been with my girl for about 6months now (we're only 16 years old). At the very beginning, she was extremely happy to be with me and she seemed this way up until about a week ago. Recently, she's been complaining that I've been bickering at her; though, we havent really spoken much recently (she's been working and busy), and I've only been nice to her because of her schedual. Now, she brought up asking me what I think about taking a break, and this started a fight between us. We're done fighting, and mostly resolved for the most part. However, she said she needs a week to think about us and that she doesnt know were we stand. Shes also PMSing. She seems distant. This is driving me crazy, I really don't know what to do. Is this odd behavior of hers due to her womanly issues, or is she going to leave me? I havent been able to get any sleep over this.