| Quote #1
[Connie] had a quick, nervous giggling habit of craning her neck to glance into mirrors or checking other people's faces to make sure her own was all right. (1)
Connie seems incredibly self-conscious about the way others perceive her – she's always trying to get a view of herself from the outside, whether via mirror or other people's reactions.
| Quote #2
Connie would [...] look right through her mother, into a shadowy vision of herself as she was right at that moment: she knew she was pretty and that was everything. (1)
Connie's sense of self revolves around her beauty rather than any other quality (say, personality, intellect, etc.). Ironically, this sense of self is "shadowy," as if to suggest that there is nothing substantial to her beauty.
| Quote #3
But all the boys fell back and dissolved into a single face that was not even a face but an idea, a feeling, mixed up with the urgent insistent pounding of the music and the humid night of July. (10)
Connie seems unable to express her sexual desires, even to herself, except obliquely or indirectly. Her desire is reduced to a nameless "idea" or "feeling" and associated with sexually suggestive imagery such as "urgent insistent pounding."