My twin boys were born at 33 weeks and were 3#8 oz and 4#7 oz. They've always been low on the growth chart and now they are around the 1% mark. They will be 3 in two weeks and are still around 25-27 pounds. Now that they are potty trained their 18-24 month pants fall off their tiny butts. They seem to eat a lot.... Last year my Dr gave me a little grief about how small they are but we don't know how to get them any bigger. We started giving them a lot of Greek yogurt and they love peanut butter and cheese. We've also stuck with 2% milk and add in Chocolate or Strawberry mix for some extra calories. Have your twins stayed on the small side?