How to tell if a girl is shy/nervous and is interested?

i was in a class with this girl, i often catch her looking at me and i look back too
so time went by, i've been bumping into her on campus, usually just eye contact and smiles and sometimes a wave, nothing more..
i always wanted to go talk to her but she's pretty social, always with a group of ppl...but i'm shy
anyways..2 chances came and i took them, tried to talk to her
- first of all i'm not too good at starting and keeping a convo
- both times she asked 'how r u' first and then i asked back, and then like 5 secs of awkward smiles and eye contacts...and i managed to ask simple qs to break that
- well she asked for my name the second time

but i'm not sure what she is thinking, i mean she seems really outgoing with a group of fds but alone..she seems shy and nervous when i tried to talk to her

**maybe she's like that cuz she doesn't kknow me? lol

the first time, i started talking to her and 2 of her fds came by and she had such a good and smooth convo with the guy, but i think she's the flirty type cuz i always see her talking to guys lol but yeh i was just standing there awkwardly :( then i left for class lol