Really, you should not house them together, the female is just to young to allow to get pregnant. Are you sure you have a male and a female? Are you sure they are not related? Also, housing them together could also be causing her not to eat well, the other could be bullying her even though you may not see it and that could account for the size difference you mentioned. Also, you may want to try offering a bigger variety in thier diet, I think the key to them feeding well is that they get a varied diet. Also, IMO the 30 gal. cage you have them in now is not really big enough for both, muchless one at that size. Also, they need animal protiens in thier diet to grow right, it could be that the one who is bigger is eating all of the crix or bulling enough that the other wont eat them. You can always go to Walmart or somewhere like that and get a rubber maid for cheap housing to separate them, I would really consider doing so. Feeding crix may also go better if you feed in a separate container instead of thier housing, some dragons just dont seem to like chasing crix.