Well, I will say that I had someone give me four meat birds (aka Cornish X) and they were WAY overgrown. We had planned to butcher them right away (they were going on like 9 months old)... But decided to keep them for a few days to make sure they were ok (they lived in a dirty area, and hence were really dirty)... Well thank goodness we did, because it turned out that those birds had a bad case of Cocci (they would die in the next few weeks) and MAJORLY bad bumblefoot, which would make us sick if we ate it.
That being said, you could probably keep her for awhile if you limited her feed, but she will continue to grow, and it will become painful for her to simply breathe.