Was she flirting with me? Does she like me back?

During this conversation, she seemed a little nervous... she would smile back at me, looking into my eyes, laugh a little even if it wasn't funny (i didn't tell any jokes). When I first said hello to her and she said hi back, I kinda froze for a second. I know for a fact my face blushed when I smiled at her... I'm a shy guy... LOL After my face got red, she smiled and had a little laugh.
This took place in my college library:

Me: "Heyyy..." "How are you?"
Girl: "goooooooood."
Me: smile... pause... I can feel my face turning red... lol i'm shy
Me: "How was you day?"
Girl: *smiles, looks away for a second, "Ahhumm.... it's going pretty good...yahh..." **SHE SAID THIS VERY SLOWLY AND SOUNDED NERVOUS.
Me: "That's good!" "Hey what are you studying there...?"
Girl: "Chemistry... my final is on Monday."
Me: "Ahh... haha.."
Girl: "Did you start studying for finals?"
Me: "Yahhh... lol"
Girl: "By the way, thank you for the candy gram!!"
Me: *pause* .... you're welcome.
Me: "Well I gotta go print something out. I will talk to you later."
Girl: "OH okay see you later."

While she was speaking, she would smile, laugh/giggle a little like she was drunk, her eyes seemed to light up, she was showing her teeth a little too.

I've seen her talk to other people, including guys, and she doesn't seem to speak to them in the tone she does with me... is that cause she's flirting or not?

What do you think? I asked her out before and she couldn't make it for a legit reason. When I asked her out, her original response was "it was sweet of me to ask her and she would love to go."

I think you might to flirt more.. she might enjoy a good flirt, but dont really feel to go out with you yet..

Judging by the way you explain it, I believe she's definately into you.... I also think you both are very shy when it come's to keeping the conversation going... Heres a fiew tips on how you can keep the convo going next time you see her.
1.) find common ground (what do I mean by this?) Find something that intersests her. ask her open ended questions, meaning she'll have no choice but to respond back...
2.) Try to push her out of her yes and no single answers... Most women love to talk, so if you can find something of interset to talk about, she should have no problem talking.
3.) pay close attention to what she is telling, and always continue to ask open ended questions about the subject at hand.. Before you know it, you both will be engaging in convesation... You'll feel and look confident.. This will make her fell comfortable with you...

hope this helps!!!
Tico Jett