I think the best thing tis to keep an open mind on all of this. It sounds as though the serious commitment part really scares her and she may feel things are moving really fast and she's not sure if she's ready to settle down. She also has to think of her daughter as well and that could very well be the contributing factor in this. I would just keep talking with her and find out what's going on in her head without sounding as though your begging for her to stay even though you want to. Just ge tthings out in the open and ask her what she wants, or what she expects out of your relationship.
If you can't handle the thorns, don't crave the rose!!