A person shouldn't be expected to go through life without support. You are one person and can't do it all yourself. If someone is offering to help take it. For starters, your parents most likely have more experience with newborns than you do. Allow them to guide you.

Don't feel guilty! You should remember that your parents are your family, therefore they are your daughters family too. Don't push yourself away from loved ones and drown in that. I don't know anything about your situation, nor your life, but if your ex is the father of the child I feel that he should be helping you. She is not just your child. she is his too. It's his responsiblity as well, and if he is around, make him pull his weight. He isn't the one dealing with postpartum, and if it's too stressful for your family and him to deal with, why are you doing it alone? You shouldn't be.