Calories and fat no longer matter to you! :)
You can eat all food you'd like as long as you eat high protein and low carb. It sounds like you were given RNY advice which is unfortunately what you usually will get from people who truly don't understand the DS. Before my surgery I had to visit a dietitian who gave me printed sheets on how to eat after Gastric Bypass. I told her I was having a DS and she "same thing"! Well its not!
Fat is OK, however in the beginning too much may bother you, later on you will be more tolerant. I eat bacon, cheese, whatever daily and I have maintained. Eating fat is important since you don't metabolize it the same way anymore, your body will need it for your hair, skin, etc. Eating chicken is great. Its a great source of protein, but now you don't have to skip the skin!
Be careful of the fake sugar! I find, and everyone is different, a little sugar is better for me than the fake stuff, it usually bothers my stomach, and I don't care for agave or stevia. And since calories don't matter anymore, why not eat what I like. As long as I don't go crazy, I'm OK. I guess like with anything moderation is best.
Early out eat small portions and see what bothers you and what doesn't. The gas can be really bothersome but you'll find your way. Just take it slow.
Goo luck!
Nothing will change if you don't have the courage to change it!
And stop calling me "Shirley!"