Sounds great!! They gain weight so fast those first few months. My dd was 4 weeks early and 4lb. 15oz at birth and two months later she has more than doubled her weight...just amazing!!! Her twin brother is right there has not quite doubled but he is still ahead of her by a pound...
Sounds good that she's gaining weight. My little guy put on almost 3 lbs in a month as well (he was 2 weeks early, 5 lb 4oz at birth). The doctor was really happy with Kyle's weight gain! Congratulations to you!