Lunchroom Approach

I met a co-worker yesterday in the employee lunchroom, there was a guy and then this black girl 6, cute, 21 yr old. I started up a conversation that would include all of us, it was something like I haven't seen any of you around here are you new? I was actually working an evening shift opposed to my normal morning shift which is the reason I haven't seen them before. The guy was new only about 2 months, while the Girl has been there about 6 months. From there I moved onto what departments they worked at, and before I knew it we all were in a conversation. A strange thing occurred those as we were getting to know each other, b-day's came up and the girl said Sept, I then said Oct, and the guy said Nov. In that order we revealed to each other, then we asked for days, and I started with 22nd, then the girl answered with the 23rd, and believe it or not the guy said the 24th.

Anyway I was changing the subject to music by taking out my phone and about to play a song from phone, when the guy had to get back to work, leaving me alone with the girl. She liked R&B and rap but I didn't have anything on my phone, although I like some of that music so I played something close to it. With the music playing I could now barely hear her when she asked me a question so I said let me move closer cause I can barely hear you now. So I sat right across from her instead of across the room like I was. The move turned out to one of the best things I could have done, in that we started having a real conversation now. It was going pretty well, and it seemed like she was interested in me, but when I did a future projection it seemed to change.

This is from what I remember how it happened:
She asked me what I was like in HS, and she mentioned she was somewhat of a tomboy
Me: "Ya I don't really see you in a frilly dress or anything"
Her: "Ya that's not really my thing"
Me: "So what would you wear if I asked you out on a date then?"
Her: She smiled bashfully, and was eating a sandwich at the time, so I caught her with her mouth full. When she was ready to speak she said "That might pose a problem, you see I have a BF"
Me: I immediately said as sincere as possible with a big smile on my face "I wasn't asking you out, I was just wondering" or something very similar to that. "Besides I don't date co-workers, it can get too messy"
Her: She said something in response to that like "oh ya I see what you mean" then continued with something like "well back to what I would wear... I'm not sure what I would wear." She was still smiling with her bashful face, I guess I took her for a surprise.

Now from what I can tell analyzing this, I would say that either I pushed it too fast, or perhaps it's the way I might have said it. We moved onto another topic after that and kept talking for quite a while before I had to get back to work. I probably should have still ended it with something like, "well you seem pretty cool" and went for a #close, but I didn't think of it at the time as someone else came in and started talking to her, leaving me out of the conversation. I knew I would see her later and did indeed see her later that night as I had to go around to all the cashiers (which she was) and collect hangers. Unfortunately when I got to her, she was on the phone, and taking care of customers. So no interaction occurred, Aside from the friendly Hi, and a smile from each of us.