Really depends on the cat, some of mine have huge appetites others less so, if she is asking for more than I would allow it...12 lbs isn't overweight by any means, plus I have found over the years when feeding a good diet like you are, doing most cats don't over eat. It's mainly the high carbs, gravies and grains that aren't adding to the nutrition but are adding up the pounds
Give it a go, if you think she is getting to heavy by doing so I would cut back the free feeding dry.
Btw, did she manage to regain some or all of her hearing??