oh, how cute is that? I wanted to compliment you on putting your hand (or, someone's hand) into the picture to provide a point of comparison. That's so important.
I sort of wish people would include a common object or ruler in their pictures. I sometimes crochet tiny things and whenever I post a picture of one I put it next to a Diet Coke can because I figure, everyone can understand how big a Diet Coke can is...(well...one time it was so small I put a quarter in the picture...but it's the same idea: put something people can relate to in the picture)
To answer your question, Yes he does look about 3 months of age. Some chameleons grow faster than others but he looks just fine for 3 months. Enjoy him while he is that small he is going to get so big so fast in the next few months.