How can i tell if i have early pregnant belly or a typical teenage bulge?

Showing a Bump: Every women "shows" a pregnancy differently. First time pregnancies usually show "later", around the early second trimester. However, alot of this is influenced by her body type and bmi. Subsequent pregnancies tend to show earlier due to abdominal muscle laxity (in general). Some thin women may not show until later as the uterus grows.