Based on appearance of the tail base, plus the coloration (which is not the primary determinant) and the blue cheek patch- I would normally say you have a good looking female there, BUT, there is an earlier post in this same forum of a cham that looks like yours and it "blossomed" into a male. I have had young males seemingly "subvert" their masculinity when they lived in a baby/juvenile colony which contained an Alpha male. I always assumed it was an instinctive or unconscious self preservation tactic. So, in your case, it may just be too soon to tell.
I would say female 99% sure if not 100%. There is clearly no bulge in the first picture and at that age the bulge would be developing and defined. Colors also say females as others have posted as well.