One-itis is so common in highschoolers, for both genders, and it really messes up the works. Not only are you AFC af, which is understandable since you're young, but highschool girls and a lot of grown folk game isn't even geared towards that world. Teenage girls are a mess. Oh boohoo some boy doesn't like you. Let's cry and cut our arms for the next 6 months over it. I mean seriously.
All you can realistically do at this point is move on and game other girls, and let her know you are doing it if you want to even bother with her still. Or just go for her one last time and ask her out and escalate the whole time to let her know you are to be regarded as a sexual being and that is your intent. You should always be escalating all the time with any girl you are interested in. None of this backpedaling and second guessing yourself. It just gets you nowhere so what's the point in bothering with it.