Okay, so i asked this girl out and said i will call her to tell her the time and date. Fastforward a week later, which was yesterday night, i called her and she didn't pick up.

Now it has been more than half a day and im absolutely sure shes concious and aware of the missed call. So whats up? Why isnt she calling me back?

i'm going to call her again tonight and keep calling everyday until i get her because i figured i've really got nothing to lose, but i'm afraid i might get the 'oh, i've got this thing... Blah blah' This is like seriously bumming me out. So please give me some expert pua wisdom.

To put things into perspective, I'm 20 and shes 18.

do not keep calling her, you DO have something to lose you are coming off as desperate. then you become "that creepy" guy she met the other day. she could have a perfectly valid excuse why she didn't get back to you.. you can either wait a 1-2 days before you send a text her way or just wait till she gets back to you. You want to make it seem like you didn't even notice that she left you hanging or that YOU were too busy and didn't notice.

the age thing does not matter, the gap isn't all that much really. most college aged girls are 18-22+ so its not an issue.