Weight gain??

I have a home scale and last week Tuesday I weighed our daughter and she weighed 7lbs, 2.5oz. I was supplementing with formula every feeding up until Thursday. I stopped doing an every feeding supplement and have been letting her feed until she is done. If she still seems hungry I will follow up with some formula as I want her take a bottle too. Well today I weighed her and my scale read 7lbs, 12oz. Is it possible for a baby to gain that much in 6 Days? She is 4 weeks old. Is she going through a growth spurt? She has been awfully hungry lately showing hunger signs a ton. Am I overfeeding her? I want even sure how much she was getting when I would feed her. Please help me with these questions... first time mom here.