When I had my last c-section, my doctor said I shouldn't have anymore children. Because my uterus is very weak and that it's barely staying together. How can I change that I would love to have another child?

Surrogacy/adoption. Sounds like your uterus has been incised in an unusual way that can predispose you to complications in future reproductive attempts. Is surrogacy/adoption an option for you? You may take a life-threatening risk if you ignore your obstetrician's advice!
How old? How old? How many kids do far? What's your nutritional status? You might need to see a high risk ob/gyn for second opinion.