2,500 sq. ft. is not too much for a 3 person family. As your child gows, you will use the space for an office room, game room, exercise room etc. The question is do you want to spend the extra money for maintaining a larger home? You can even close off heat/air registers to part of the home until you need it to hold utilitiy bills down. However, maintenance costs, utilties, insurance etc will be higher than in a smaller home. It is a choice. Location, whether the home "feels right", and quality of the home are important.