Most Helpful Girl
I think she's a little tentative, but she is definitely flirting with you and likes you otherwise she'd make up an excuse or say no. :)
If she makes effort to keep conversations going also and/or messages you first, don't worry about how often you two talk. If it's just you making all of the initiative then take a little break and see if she initiates a conversation at all. The tricky thing is you don't want to seem like you are not interested in talking to her, either. So if you just drop off the face of the earth for a few days she might start to wonder. Maybe just message her less? You could send her a text in the morning and tell her something like : "'Just saying hey. I hope you have a great day today. :)" and I can guarantee it WILL make her day. But then she doesn't feel like she has to keep a conversation going, either.