Glad to hear everything's gone smoothly! I have a coworker who had gastric bypass a few years ago. She is a constant nibbler. She eats pretty much anything she wants now, but it's always just a tiny bit: half a can of soda, a handful of chips, half a sandwich, etc. She also tells me she's not supposed to drink anything when she eats because her stomach isn't big enough to hold food and liquid.
Your sister looks great! I've considered having weight loss surgery, but I am seriously concerned about the extra skin and how fast it would age me since I'm only 25. My coworker is 52, but she looks like she's in her late 60s now that the "fluffiness" is gone from her face. Padding does keep faces looking young.
Just keep drinking water! Water keeps your skin young. And don't forget you're already beautiful, you'll just be healthier!