I'm 18 and I want to get a small tattoo of a peach on my right breast. My breasts shouldn't grow to be much bigger than they are now, but if they do, will my tattoo become distorted ir stretch as well?

Depends on where you put it. If you ever get pregnant and/or breastfeed (or gain weight as you age), your peach may become the size of a watermelon. It'll give the medical staff something to chuckle about.