The answer to "Should I ask her out?" is almost always yes. The answer you will get to asking someone out might not always be yes, but if you never ask, you will always be wondering and coming onto advice sites like this asking for help on ways to get over her.
Ask her out. Ask her to prom. You can even say, "hey, I was thinking of going to prom. I think it would be cool if you were my date. What do you say?" or something more in line with the way kids talk today.
Good luck.
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