If I could give one thing to the younger women of the world, it would be; 

Your body is amazing, just the way it is.
Curves, straight lines, either is perfect.

What Hollywood/Media portray is not ideal, it is morphed beyond 99% of what's possible.

Your body can create life -> you can make another human!  Because of this, your breasts will change, your hips will spread, your butt will follow. Embrace it.

If you feel beautiful, people will see beauty.

Wear clothes that fit you properly, and no matter what size you are, you'll look pretty.
Make up is camouflage if applied too liberally, let it accent you, not hide you.
Your butt, boobs, or belly do not have to be exposed to be 'hot'. In fact, what you leave to the imagination usually is more alluring. Accentuate, don't advertise.
When you look back at photos of yourself as you age, you'll regret having so many insecurities. Look in the mirror everyday, find what you like about yourself; ignore the things you think are imperfect, because, you are the only one who sees those things.
There will be moments where you find yourself wishing you could be ~ thinner, skinnier, taller, blonder, round faced, oval faced, curly hair, straight hair, smaller butt, bigger butt, bigger boobs, smaller boobs, flatter abs, curvier hips, smoother thighs... Open your ears; you'll hear similar complaints from other girls/women. You are flawless, because you are exactly the you you're supposed to be.

Finally, if you put on more weight than what makes _you_ comfortable, don't sweat it, realize you are a work in progress, and with progress comes change.