hehe, yes, you definitely can think things through endless
thats a good thing - persistent thought that is - unless its just going in circles.
anyway, heres the answer to your dilemma.
DO NOTHING. do nothing other than ONE THING.
and that ONE THING is..... have fun!
be happy. be content. enjoy life. smile. say hello to everyone you meet if you want. next time you see this girl smile and wave and move on.
if you are close enough to talk to her then ask her how her day is going.
FORGET outcomes. forget closing. forget her as a romantic option. forget all that stuff for now.
just walk around with a 'I'm a guy loving life" attitude and if she's interested she'll find a way back in to your life and you'll get your shot to ask her out at some point. if she's not, then no big deal
this is why i keep telling guys, you can't FAKE it. you gotta work on yourself first, you gotta get your positive vibes about life going good and strong. then closing women is a joke. when a woman sees a nice guy, who is confident, enjoying life, etc. - its the equivalent of a man seeing an hb10 walking down teh street in cut off cameltoe jean shorts and a wet white tank top with perfect t*ts.
think of how that stops you in your tracks and thats how women react to guys who have their sh*t together and are laid back and most of all friendly (not just to them, but to everyone!).
you DO NOT have to try and figure out all the different ways you can behave and then try to figure out all the different ways she might react to all those ways. thats making her the prize.
all you gotta do is walk around enjoying life and being the prize. women will make themselves available to YOU if you do that.