Have you shared with your friends that you are following a low carb diet? If not, this is where I would start. From your description they seem to be very caring and hospitable. Maybe if they had a general idea of what you prefer to eat and what your prefer not to eat, they would offer things you prefer.

If you don't want to tell them you are on a diet to lose weight, tell them you are avoiding certain foods that cause you issues. This is not a lie.

By the way, you probably didn't really gain 2 lbs from what you ate. Just water weight. It will be ok.