no offence my friend, but i think you are being slightly paranoid- happens to me alot, but this is about you. a girl wont pertend to liek you, and risk a relationship if she doesnt actually liek you!
She already knows! That is usually the hard part. Go up and talk to her with confidence. DON'T be cocky! Women/girls love confidence but usually cannot stand cockiness and arrogance. Be yourself....