Birth control and gaining weight...

Brittany • Brittany • 24 • Tom is my saving grace. I love you <3 6.30.14 <3
What brands of bc don't cause you to gain any weight? I am 5'4" and 130lbs and I love my body. My boyfriend loves it too. 
Would hate for my body to change... 
I hear IUD can be dangerous and cause infection. One of my old friends from high school did the shot and hated life due to side effects.
Me and my boyfriend are very sexually active. I read about a few pill brands some can lower libido...
Any suggestions???