I have a very serious and kind of embarring question about puberty...?

ok so im 14 and im very scared because all my friends are like yeah im 6 inches or im 5 but my is 4.2 inches and i am very scared it wont grow. Do you think it may be because i master bate to much or is it hereditary i am very scared it wont grow and i will be an outcast when im older so pleas can some one help me. Thanks very much