Chemistry for chemistry

What size should I get? **Baby tee size**? - baby junk food tees

I want to buy a baby shirt, but have no idea what size should I go for. My height at the regular price is S. Do you want me for a larger size? East?

This is a I want: http://www.stylinonline.com/baby-tees-dc-comics-girl-power-junk-food.html