Does a shy girl at work like me back or does she really not like me and is just being polite?

Anonymous
Yeah, so this'll probably sound very daft, but I started a new job a good few months ago, and there's a colleague that I've really started to like.
Some of her friends there told me that she is very shy, and suffers bouts if depression. I never thought she'd even give me the time if day, but once I'd plucked up enough courage to actually speak to her (I'm fairly shy myself) it turned out we've got a whole load in common, very similar interests, sense of humor etc. We seem to get on really very well, She laughes at all my silly stories and jokes, and really seems to listen intently to them. She also displays other "classic" Signs of maybe liking me too.
Tho on the flip side she'll also completely ignore me. She'll walk past me at work and look to the side, I'll say good morning and smile and she'll look me in the eyes then look away without saying anything, as tho she really can't stand me.
I've caught her looking at me out of the corner of her eyes, and at other times, and she looks away when I see her, tho I fear this is more out if her worrying that I'm going to bother her.
It went from her asking me to join in with some gaming stuff, to her hardly saying a word to me almost overnight.
She knows I like her, and she was messed about by another guy late last year, so maybe that's got something to do with how she's acting. There have been a couple of awkward moments, but at no point has she been cruel or nasty, and has had many chances to tell me to go away etc but hasn't.
I've been single a little while now so all this may seem really stupid.
Does a shy girl at work like me back or does she really not like me and is just being polite?
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