It's normal for your body to change size in general! It wouldn't change size due to you not masturbating, though -- it's likely just body growth as per usual.
Puberty most commonly starts with testicular growth. During the whole of puberty, the penis and testes will eventually grow to their adult size. It’s common for the length of the penis to grow faster than the width of the penis and for testicle growth to start before penis growth. Growth of the penis and testicles often is not complete until the end of puberty.