What are your temperatures and humidity like?

What are they being housed in?

What are you feeding them and how often?

Like Snakey said, have you ever had them probed to be sure of sex?

This time of year is breeding season, so it doesnt surprise me that either animals are off feed.

Males and females aren't cut and dry in size, In my experience my males are growing faster than the females. Though generally females are larger, males can certainly get quite large and females can stay rather small.