Breastfeeding Discouragement

Laura
My daughter will be 2 months old on the 16th. I have been EBF her with the occasional formula bottle. However, I feel discouraged to continue to do so. My younger sister pointed out that my daughter isn't as chunky as other babies around her age. At 1 month my daughter weighed 8 lbs 7 oz. Her lowest weight was 6lbs 3 oz. My daughter wets plenty of diapers and has at least 1 or 2 bowel movements a day. I don't know why my family can't respect my choice. They don't understand that pumping isn't as efficient as my baby nursing straight from my breast. I want to continue to exclusively nurse until she is 6 months or longer. When I do pump I can get anything from an oz to 4 oz. It really depends on the amount of time that has elapsed since her last feeding. I'm tempted to schedule a weight checkup to see how much she weighs now. I don't think I can wait till the 23rd for her well baby check-up. What would you mama's suggest I do?