I agree, I think you have a meat bird on your hands.
They grow a lot faster, so she may begin to have some leg issues. I'd be inclined to give her 1/4 tablet B-Complex once daily for a week, then taper off to 3X a week. The B2(Ribloflavin) can help with leg health and B Vitamins are water soluble, so there shouldn't be a concern of giving too much, any excess is excreted in the urine.
Once she gets older if you plan on trying to keep her and prolong life, then you'll need to encourage exercise and perhaps limit her food intake. A few here on BYC have successfully kept a few that lived to be around 2yrs old before they declined, but they were managed carefully. Sadly, many won't make it that long since they are bred to be processed at around 8-10wks or so.