N.J.
For someone like your father you need to arm yourself with knowledge. Do a little research and find out how many calories a nursing mother is supposed to consume in a day. When your father makes a comment respond with, I'm allowed to eat bread--my body needs the carbohydrates to feed your grandson. Educate him on the amount of calories it takes produce breast milk and how you are doing your best to give your child all the nutrients he needs by eating healthy yourself. Men have no idea what carrying a child and then nursing a child does to your body. Today's men are encouraged to read parenting books, etc. My Dad sat in the waiting room until after I was born. I often tell people that my daughter sucked my calcium out of my teeth. After my pregnancy I had 16 cavities. All because I didn't consume enough calcium. So, again, arm yourself with knowledge and stick up for yourself. Just make sure you've got good information first, I love starting a conversation with "according to the American Medical Association..."
~N.
P.S. Congratulations on loosing all that weight plus some. Its not an easy task.