OK so I love using cartons for the convenience but it's costing me a fortune. Ruby has never had powdered milk, she's almost four months old now. I was wondering whether I would switch to powder now to save money. Has anyone fed their baby cartons then switched to powder? Any experiences? (as in effect on the baby, I know how to prepare it correctly and do not demand feed, I have a routine, so no probs there.) Thanks in advance!