Was your LO early? My DD was born 3.5 weeks early and also weighed 6lb 2oz. When we left the hospital she was down to 5lb 10oz. She has gained weight like you would NOT believe, but her length has increased at the same pace. She's basically following her own growth line. She was around the 10th percentile for weight and length at birth. At her 6 month check up she was at the 75th percentile for both length and weight! She is a whopping 20lbs, so more than tripled her birth weight already, but she's not overweight. She's chubby, but cute baby chubby, not OMG what a huge baby! Her biggest growth spurt was between 3-6 months. I think she only wore 3-6 month clothing for about 1.5 months! I really think they only eat if they're hungry, so if she wants to eat, let her. She knows what her body needs!
Also, I think your DD weighs less than mine did at her 2 month check up. I believe my DD was a bit over 9lbs at her 2 month