First of all, you're talking about where did you go wrong. If you were being your authentic self and keeping everything truthful, you did not go wrong at all. You also say she has alot of guys talking to her. When you talking to a fine ass lady, you're always going to have competition. You gotta believe in yourself and have something that makes you stand out from the crowd. An important key is to not convince her to become attracted to you. Stay authentic, read her signals, and act upon that. You asked her out on a date and she went cold. YOU should go cold too. Don't text her anymore. Stay invested in yourself and don't worry about this girl. This girl is probably low self esteem. If she likes you, she'll probably come back. (I speak from experience) I went through something similar to this recently. I held on to it for a while & felt kinda down and looking back at it, its not really a big deal. If you're in school, put yourself out there more and meet new people. You'll be fine. I recomend you read Models by Mark Manson.

Off topic question : what messaging app is that?