two biological sisters in the cong I went to, one was skinny one was overweight (almost obese), guess which one was a preemie when born.
Also, I've heard Al Roker say, I think he mentions it in one of his books he was a preemie also, I'm sure you remember how he looked before he lost weight, I'm not saying your daughter is going to be overweight, but when you look at the two folks I mention, you would hardly suspect them to be underweight at any time in their life. Your daughter looks great, no more worries, no need to say she's on the road to recovery because she already has.