You've had sex with another girl, she's dated another boy. What exactly is unfair here? I think this is really petty but if anyone should feel disgust (which, in this case, nobody should) it should be her. I mean, you're demanding perfection but that's not what you're offering is it? It's okay to hope to get the better end of the deal but at the end of the day you don't have the right to demand more from her than you can give yourself.
Can't help the way you feel I guess but it's unrealistic. I've never been in a 'proper' relationship either but I'd not turn someone down over that, seems silly and you could miss out on someone special.
No, that doesn't seem logical. I get if you're insecure about it, but not dating her solely because of the difference in # of relationships seems silly. I will add that I don't think this is uncommon, since guys tend to initiate.