A girl flirts but says she hates me?

so I'm 15 and there's a girl who is 11 we both have very protective parents so the odds of sexual activity's is low I've had a crush on her for a long time is it immature or wrong for a 4 year gap she has said behind my back she does not like me but anytime someone says a sexual joke or something like that she gets awkward but only around me she flirts and seems to care about telling me about her day
A girl flirts but says she hates me?
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