You can definitely not house a female dragon that small with a male dragon twice her size. You not only have to worry about the dominance issue, but it is very possible she will start ovulating way to early for her age whether or not the male breeds her successfully or not and could very easily cause her to become egg bound.

I would not even house an adult female and male together except for mating and then removing the male to his own enclosure. He will harass the female more times then not.