I wanna a bigger but :(

I'm super skinny so I don't want to get implants because it wouldn't look natural but idk what else to do. I'm 18 & all throughout high school people told me once I started having sex I'll get thick... that was a lie. Then I got pregnant & everyone told me I'll gain baby weight.... that was a lie. Even got on birth control the doctor said I'll gain some weight... that was a lie!! What else to do???