My LO will be 4 weeks old tomorrow. For the first two weeks I breastfed and he gained 5oz going from 6lbs 14 to 7lbs 3. After this I decided to switch to formula for various reasons and fed on demand and he gained 1lb 1oz up to 8lbs 4oz. I'm worried that I'm feeding him too much. His feeding varies from 2oz to 4oz every 2-4 hours. He will be weighed again tomorrow. How often should i be feeding him? Should I be feeding on demand like breastfeeding or should I try to get him into a routine? Thanks in advance for any advice.