Tanner stage 4 at 20 years old. normal or late? i feel like i look 15 down there.

Typically the 5: Tanner stages that describe sexual development in puberty end at about age 15. You're right, Tanner stage 4 usually represents a 13-14 year old. Incomplete development of secondary sexual characteristics in males usually results from inadequate testosterone secretion which is most often caused by a defect in the pituitary hormone which stimulates the testicle. See an Endocrinologist.Good wishes