I'm confused, is the girl I'm dating pulling away from me or is she just simply not very mindful?

The girl I'm dating, I work with and she works the weekend shift. I work with her on Monday's and Friday's. We started dating 3 weeks ago, but we have covered a lot of ground in that short time. Just as recent as yesterday, we were talking about when next year we should get married. We've talked about having kids together. We sit together at our breaks at work. We really hit it off, and she says we have a good vibe. I'm very punctual, if I say I'm going to do something I do it, with her it seems like she doesn't care. I text her at my break times at work when she's not working, but she doesn't when she's at work. I asked her yesterday if she wanted me to meet her after work and go do something and she said she'd let me know, but not a text or phone call. I called her when she was on her last break and I left a message, still no response and she's been out of work for close to an hour now.