Mike, think back to the long ago. Maybe not so long for you, but bear with me.

Back in the days when Mom still fed you, before you struck out on your own, when you not only could but did on a regular basis eat TWO large pizzas on your own, by yourself, before you'd go home for dinner.

Teenagers, mostly boys in the human species but particularly girls with Boas, NEED FOOD IN QUANTITIES.

She may grow faster, she may get a tad pudgy, but for the next few months I'd just feed her what she wants. A couple maybe even three mediums. You could try a large rat but several mediums will sit better once she eats them.

Once she hits the 6 foot range she'll slow down and then you can feed her larger prey items less often.

My two big girls now only eat every couple of weeks but they'll take large meals, 2 or 3 breeder size rats for the 7 footer and at least 3 breeders or a nice fat bunny for the 9 footer.

I've raised a fair number of boas and what you're describing are growing pains given that everything else in her set up is spot on.