Sexing young dragons is very hard, if not impossible. A dragon that appears to be one sex at two months may very well appear to be the other at five months. I have purchased several dragons that later turned out to be the opposite of what the breeder I purchased them from thought they were. An example is Puffette; purchased at five months as a boy and named Puff, Puff looked like a boy to me also. However a couple of months later; boom, I have a Puffette. Not that I loved her any less, but it happens. So, I will not guarantee a sex, but I will promise to do my best to guess at the sex correctly.
Boys tend to have larger heads in portion to their bodies than girls. Beyond that tendency, to sex your dragon, gently hold it in one hand supporting all its legs. Lift its tail gently up. Not too far or you’ll harm your dragon. Under the tail is a slit at the base, above this is where you’ll look. Boys will show two humps with a small dent in the center, these are their tentacles. Girls will have one hump in the center or it will appear to be flat. Pictured are examples of a boy and a girl to help you determine the sex of your dragon more easily.