Scared to death to gain weight during pregnancy! 😫😭😰

Just posting this my heart rate is going up. My husband want a baby so badly and I have the hardest time letting it happen. I have a very hard time losing any weight in general. I'm scared to death to become pregnant and gain a bunch and never be able to lose. I don't know what to do makes me mad at my self I can't just be that thin mom that doesn't gain an oz. I'm so ready to be a mom but scared I'll never be able to manage my weight or lose it when I'm done. Help me any advise 😫