Sounds to me like you are a bit shy too, or maybe it is that you are just new at this approaching girls thing (since you said you didn't have much experience with this kind of thing).
I know shy people can sometimes feel unapproachable (especially if you are attracted to them), it just almost becomes intimidating. That social phobia vibe just makes it hard in taking the effort to talk to them first. However, you have to overcome that & go talk to her. She can look your way & blush or smile all day, but you won't be fully satisfied until you talk to her. Until then you won't really have any good indications of whether or not she may be interested. And too she won't know that you are interested either. Until you make that bold move you (& maybe her) will continue to question each others every move (& you could read her wrong).
Just walk up to her & start a conversation. Smile a LOT & KEEP eye contact! Show her that you have confidence & that you are enjoying talking to her. That more than anything should make her feel more at ease. Just be yourself! You have nothing to lose!
