Weight Help 😭

Okay , So me and my boyfriend go out to eat a few times . And well I think I have gained weight but he says I'm not fat and I look good and sexy and all this . But on the other hand my mom says I have gained a lot and that I need to stop . I think I have and well I wanna go on a diet and idk if my boyfriend will like it because he loves my body just the way it is . But I do think I'm fat 😭 idk what to do . Help!!