At what age is a female body fully grown ? ?

Generally by about 20ish

13-25, give or take. 

--  Mostly between 18 and 22. Some finish earlier and some finish even later., It depends on the individual female.  Breasts alter in size (bigger and smaller) slightly during menstrual cycle and hormone levels, and change even more when pregnant and breast feeding, and never return fully to their previous size and shape.

Typically between the age of 18 to 21 - must like males.