Girl works at starbucks part-time same as me, easily a HB10

I was away out of town for a week and came back fancied a coffee so I went into work to order one and she was there too, unfortunately the week I was away it was her 21st birthday, soon as I got in she shouted my name and smiled (even though she was serving other customers) and she was like asking me the usual whether I've brought her anything etc etc, then I got to the front of the line and got served by some guy my mate asked me if I wanted to go somewhere with him on saturday and I was like yeah I'm up for it, then like 20 secs later she asked me when I was gonna go out downtown with her and I was like whenever and she asked me whether I could go on either Friday or Saturday and I just said I'll be able to do it on Saturday (without even realising I just said I'll go somewhere with my mate on the same day 20 secs ago) soon as I said that I would go her face lit up loads, and I asked her who was going and she shook her head and said just me and you I guess but then another guy working said people from work are going out on the same day.

I'm the most social guy you could ever meet, whenever I'm out I'll be the center of attention, however whenever I'm around this girl I pretty much melt, any other girl I'm great with.

I'm just not 100% sure she likes me, sometimes she acts like she does just not 100%.

Another positive/negative (not sure) is that I'm 90% sure she knows I like her as when I was out one time with her best friend I made out with her and accidently told her that I liked the HB10, and other times my mates have pretty much hinted it to her, and I nearly told her once too.

I just don't want to say I can't go now as that would let her down loads, I just don't wanna go out for it to be awkward, I wanna loosen up but not embarass myself if she doesn't want anything like that to happen between us.

I've asked my mate if he would come with me and he said he could, but I'm not sure if that's the best option to take him incase he gets in the way.

I'll be seeing her tommorow before we go out and not sure what types of questions I should ask her.

What you guys think of this?