She didnt pull the boyfriend card, she actually HAS a boyfriend.
Firstly, good effrt for having the balls for doing what you did. Kudos to thaT.
Now, Critisicms.. Whats with the coming back? Very very bad.. It makes you look desperate and that she is you only hope of a 'number' Why didnt you just ask for it straight out.. I mean shes a nice girl, your a nice guy it perfctly normal to as somene for a contact numberif you like them.. Instead of all the games and tricks you 'puas' like to employ why not just say..
'you've rubbed off pretty good in the last 10 minutes, i hope its not too forward to ask you for your number at this point..?

'
Dont overcomplicate things.