Don't worry...you r doing good(much better than me)..but don't believe even for a second that she is actually reserved, or a "good girl" or that she was awake just to wish you happy birthday..@pranshu sorry I missed the point here! She has told me herself on the 3rd date, "It's better if we wait for sex, but once you do it's worth it."
I think it's time.
These are just tricks to hook you and once you are hooked, she will suddenly go cold to test you..keep a side chick ready for that period so that you won't give in and call her like a little b1tch..