Enhanced crb scared]?

i have just had my fingerprints taken for my crb check and was told my crb shouldnt take more than 2 weeks now. i have never been involved with the police ever but am still worried about my crb. is this normal? im just worried that my crb might have a criminal conviction on it but what is strange is that i know iv never been involved with the police. please can you help put my mind at ease. it would be much appreciated