Hi do not worry about the weight part if the baby is active and achieving milestones, Give food fats like ghee, coconut oil, unsalted butter, potatoes, Paneer, banana, cheese etc in baby's diet regularly.

You can include protein in the diet .. banana milkshake helps.. give eggs .. little bit of outdoor play is helpful too.

<a href="http://app.babychakra.com/article/3779">Baby Weight Gain: What Helps And How</a> 
<a href="http://app.babychakra.com/article/3354">Kiddy Kitchen: Toddler Weight Gain Special</a> 
<a href="http://app.babychakra.com/article/2623">Understanding Baby Weight Gain</a> 
<a href="http://app.babychakra.com/article/4271">Healthy Food For Toddlers: 5 Quick Recipes</a> 
<a href="http://app.babychakra.com/article/2529">How to Raise Healthy Eaters?</a>