How to add more curves to my figure?

I'm 5'7" female, 127 lbs, 21 years old I want to add more curves to my figure (putting on more weight and looking good) I'm size 5 and my goal to be size 9 or 140 lbs. It's hard to put on weight and I eat all I can and stuff myself at every meal until my stomach hurts. I drink juices, whole chocolate milk and drinks with calories instead of water. I add olive oil to sautee foods or just drizzle it over my dinner. I add whole fat yogurt to my breakfast fruit smoothie. I even stuff myself before bedtime because I heard eating before sleep will make people gain weight. I don't execrise except maybe normal daily walk. But I still don't put on weight at all. How come? Do I have to wait until I have kid or age to put on weight? What other advices will you give me? My dad is skinny and very tall 6'6" and mom is 5'6" and overweight