Girls, does this make me a creep?

im 21 years old and constantly get told i look 17/18, every time i go to the gym or shopping ill get attention from 15-17 year old girls. even a girl my age thought I was 3 years younger than her! if i cant get girls my age does it make me a creep if i go for these younger girls? would they be freaked out if they found out i was 21? my friends call me "efron" btw because i guess i kinda look like zac efron, anyway thanks for answering.