How do you find out if your ex-girlfriend is still in love with you?

In addidition to the question, we became very close in the relationship and she told me repeatedly that I was the best boyfriend she had ever and she loved me with all of her heart. Our relationship just worked out and lasted for a good time, but all of a sudden, she broke it off, saying our relationship wasn't supposed to be like that, and that we were both unhappy because we had some issues we were going through with drama at school and things like that for a while. Everyone I know just says move on, but I feel differently. Yes, I'm a teen, and I know how it works. No high school relationship is ever going to last forever and they're supposed to be learning experiences. But we really worked out and I loved her a lot, and I wish I could understand truly why she broke up with me if she told me, but she says we were unhappy, while she always told me how much she loved me and said she would never break up with me ever. I don't really understand why it ended so suddenly, if all of this was the case, especially how we had just told each other how much we love each other that morning. Then, later in the day, she said it was inevitable to not end soon and it would make us happier I guess. Truth is, I was the happiest with her... Now, since we have broken up I feel like there's someway I can fix it so we can get back to our relationship, and maybe even start with a clean slate so we're "happier." We haven't really talked since the breakup, except when I asked her the next day why she broke it off, and all she could say was she was sorry and hoped I could forgive her. Since then, another guy(s) have been flirting with her, and of course its been bugging me. I don't want to lose her to someone else, especially knowing how much I love her and would give for her. Apparently, at lunch the other day, she was talking to one of the two guys that are flirting with her, and she saw me looking over at her repeatedly (my mistake). She asked me why that was, and I wouldn't tell her, only that I didn't mean to and was sorry. She proceeded to tell me something in this way: "just to let you know, 'the guy' was only over there talking to her because he was trying to make her feel better" because her relative is in the hospital. It kills me to know I can't be there for her... but I told her I was sorry about that anyways. It almost seems like we could still have a relationship, but I think I need to promise her happiness and show her how I truly feel, and tell her I love her still. She was probably the best thing that's ever happened to me... P.S. We broke up the day after Valentine's Day, just to give you a time. Is it too early to try and get her back? Does she want to have me as a boyfriend again, or is she trying to tell me she's moving on?