You made a few mistakes...some you pointed out yourself.
Telling her you were going to call her and then not was a mistake. Its okay to make someone wait...but if you tell her you will do something and then flake, you break some trust. Maybe you coulda said something like
"Well...maybe I'll call you this weekend...or maybe I'll be having way too much fun and you wont even cross my mind! We'll see! Tell me...do you feel lucky?" Yeah thats a bit corny..but anythings funny if you can deliver it. Remember: Laughter does not have to follow your joke, if you can get her laughing regardless of what you say, it will stack and then it wont matter!
Anyway: yes...she could be self conscious. DONT NEG HER ABOUT HER ACNE! But...negging her about being so self-conscious could be gold
I would keep flirting with her. If she flirts back: shes still interested and attracted. Then: do your thing! Read some stuff and dont assume you know what you are doing. Even I have more to learn and I've read anything you can name
