Hi Daisy!
The bitaeniatus sure LOVE the flies eh! Mine go crazy for them. If you haven't noticed, this particular species isn't an active one and, in fact, will remain in the same spot for day after day. Their appetites match their activity level. In another words, they don't eat much. I give my bitans a few crickets every other day.
Another thing you may be seeing is a slight winter season slow down and you'll find that some chameleons will eat less during the next few months This is normal.
My suggestion is taking the flies away completely and not not feed her for a day or two then offer crickets or roaches. I've not found the true bitaeniatus to be fussy eaters, but given the choice of feeders, they will choose the less nutritional flies. In my experience, the bitaeniatus do not seem to recognize soft bodied insects like silkworms and hornworms as food.
Dusting crickets and roaches in spirulina sometimes also helps. They seem to recognize "green" insects as being tasty.
Good luck!
Trace