I need help on this one?

I really like a girl that i have known for about 8 years and she says she just be friends but yet she will act like she is flirting with me.. and over the past year i have noticed her kind of open up to me what i mean is she used to not tell me things but now she tells me most things. like if she is sad or something she used to not tell me but now she will most of the time. these past few months she has just changed when she is around me... sometimes that just throws me off. she is one of those shy reserved girls so it is kinda of hard to figure her out.