Should I continue to try and talk to this girl?

There's this girl that goes to my high school. We're both juniors, however we don't have any classes together. Throughout the year I would occasionally see her while walking in the hall. Nearly every time I saw her she would smile at me and make eye contact. I would smile back, although I really didn't think much of it at first, I just assumed she was being nice. After a while, I started liking her, and decided I wanted to at least get to know her better, and maybe go further. I've talked to her a few times, but it was just small talk, nothing really special. She did smile with a blush and make eye contact on those occasions. Anyway, last week after school I saw her and asked if she wanted to hang out some time. I think I might have been a little blunt about it; she seemed a little shocked at first. Then she smiled and said sure, "next time we meet I'll give you my number". A couple of days later I saw her walking in the hall after school. She smiled and I went up to her. I asked if this counted as next time we meet. At first she didn't know what I meant, but then exclaimed "oh!" in a few seconds. After that she asked me for my number, which she then wrote on her hand. She said she would text me later. I guess I was kinda dumbfounded that she asked for my number. I didn't know if that meant she didn't want me to have her number, or if that meant she wanted me to ask for it, or what. I ended up not asking for it (which was probably a mistake) and started talking about what classes she had or something stupid like that. I said I'll see you later and she replied yeah. Looking back on that I didn't make eye contact when I said bye and there was a slight tone of disappointment in her voice when she said yeah, although that might have been in my imagination. It's been two days and she hasn't texted me or anything, and I don't really expect her to. If she doesn't text me within the next few days I'm thinking either a: she's politely saying she's not interested, or b: she wanted me to do something first. Assuming she doesn't text by the next time I see her in the hall, what should I do? Should I talk to her? Should I bring up the fact she hasn't contacted me since we last met, or pretend like it's nothing? I'd like to get to know her better, but I'm really not sure if she's interested or I messed up.