Dam-n man, you've been deep in the trenches of war with this shi-t, lol. Seriously, I give you props for having the balls to even do it, but obviously, you could use a little work.
I know when you're put on the spot it is hard as hel-l to do things like you planned on paper... your mind can just blank out, but, allow me to offer my constructive criticism here for you:
The first thing you should have done differently was try to incorporate a little teasing into the convo, possibly a neg. hit, and get her laughing.... The tension in that room must have been so thick she could cut it with a knife. THEN is the time to get the #, when the situation is at its peak. Also, build at least a little rapport too.
When she said she liked your tie, you might have said:
"Yeah, no thanks to you (sarcastically, with a sly grin)."
or use some joke or something.
While others may disagree, I think coming straight out with all your intentions is a bad idea. Your directness is probably admirable, but it can kill the attraction, and it looks like that's what happened. After reading the first line that girl said, I was thinking, da-mn, this guy has her, but you must have weirded her out or something after that.
When she said, can I help you with anything, you could have said something like:
"Yeah, you can start by leaving me alone this time,"
with a dead-serious tone and look on your face and strong EC, followed by a grin. I swear to you, every time I go out to eat with my dad, that miserly guy is so rude and treats all the young female waiters like bit-ches, and they actually seem to like being treated that way... they turn into little girls. That is a little extreme, but just be creative. Start acting like you own the place. This girl is paid to treat you nice... take advantage of it.... you can push her buttons a lot harder than you think, and she will like it.
I also don't think it was a good idea to hint that you came there just to see her. Flattering a girl is no way to attract her. You just showed her (whether it's true or not) that you have nothing else to do, you worship her, and you're possibly very desperate to resort to such measures. A woman will think this, doesn't matter what your situation really is. Always appear busy and like you have other things to do, even if you don't. Never let a woman know you made a special trip for her. Never show THAT much interest.
Don't ASK for the number. You, in a roundabout way, did this, adn the way you did it was unconfident. When you actually are getting the digits, THEN is the time to be direct, but not before it. Remember, at the peak of the convo, cut it off on a good note, and you simply say hey, I gotta go, but here (handing her your phone), type your number in my phone and I will give you a call sometime.... or some other variation of that. You are being serious with your voice tone, but at the same time, you are somehow telling her, number or no number, you could care less. If you're a confident guy, you should automatically do this right.
And finally, if there IS resistance, you should know that you NEVER confront it directly. By not giving you the number, and you still trying to get it from her, she had complete control of the situation. What's worse, she asked for yours instead, with complete authority, and you gave it to her. I recommend that the next time a girl says that to you, you just laugh and walk away. If she was testing you to see if she could control you and test your desperation, you would have passed that shi-t test and she would have said, "hey, wait, you can have my #, I was just joking," or something like that. When she doesn't want to cooperate and give the number out, you just laugh, tell her you understand, a BIG smile on your face, say, "well, I better be off now," and walk away.
Once again, I personally prefer to get the IL up at least some before I go for the #, and I never get serious until I tell her to give it to me, but that's just my style. What works for me might not work as well for you, and vice versa. I hope this helped some.