Overweight and pregnant with baby #2

Hi ladies. I’m 7 weeks pregnant with baby #2. My son is 3.5 years and I’m at the biggest weight I’ve ever been. I’ve gained 55 pounds with my son and never got back to my pre pregnancy weight. Now that I’m pregnant again I’m terrified to gain more weight. I no don’t want to get bigger. I don’t have the best eating habits so I know I know I start there. Has anyone been on a diet while being pregnant or did not gain any weight while pregnant and still have a healthy baby? Suggestions and advice please.