Mixed signals or disinterest?

As a shy guy [previously cripplingly shy, now medium shy and improving], I have some insights.

I suspect the largest part of your confusion is because you expect him to respond like a more confident guy.

But if he's shy, he simply will not respond like most other guys you've dated. Adjust your expectations, and adjust your behavior. This relationship will progress differently from others you've had. It will move slower, and have detours you're not accustomed to.

Reread that last paragraph to yourself out loud, to ensure you understand it. Let it sink in.

He's shy partly because his brain is different, and partly because of his learned behavior. If his signals seem mixed, it might be because he's comfortable with some aspects of your relationship, but uncomfortable with others.

Here's one way you're not understanding that this guy is different. He flirted, you responded by "pushing back," and in response "he seemed to get nervous, not as confident, stumbling over words, fidgeting, shy, and almost like he didn't know what to say around me." What did you hope to accomplish by "pushing back"? What if he's unaccustomed to girls "pushing back" when he flirts? When it comes to flirting with this guy, you're like a tennis pro competing against a newbie. He lobbed a gentle serve, and you slammed it back at him harder than he expected. Of course he's gonna get flustered, he was probably expecting you'd play at his level.

Also, you're creating a false choice. There are more options than "mixed signals" or "disinterested." These other possible options for this scenario include "shy guy who's nervous", "virgin who's embarrassed about his inexperience," "abuse survivor who sees sexuality as a threat," and "shy guy who's never dated a lot and doesn't want to come on too strong." Snapping out of either/or thinking is a great way to solve problems, because it helps you see more options.

Have you talked to him directly and assertively? Talking things over is so much more productive than fretting over hints and signals.

Shift your focus from interpreting his actions. Be direct and specific with your communication and questions. Something like this will probably resolve all your questions:

"I don't mean to interrogate you, but I'm a little confused about your expectations. I'm confused about A, B or C, can you enlighten me about your thoughts and motivations? I don't mean to put you on the spot, and I understand if you need a little time to find an answer. But I like you, and I want to make sure we each understand where the other is coming from."

Good luck!