Shy guy who's interested vs. shy guy who's not?

So how do you know? What are the subtle differences between a shy guy who likes you and is genuinely interested in you vs a shy guy who's not and is maybej just socially akward? What if he's more comfortable around other women than you...could that be a sign? This guy is really nervous around me and can't seem to form like two sentences and always looks at me quickly and then glances away and when I smile at him, he smiles back warmly...could those be signs also? Another thing is that yes, I do have a crush on him so could he be behaving this way because he knows I like him but he doesn't feel the same? Btw, I never pressure him to come around me or anything, he always seems to find a way to do so on his own but then he's so weird with me that it makes me feel like he can't stand me. I'm about to give up.