I'm barely eating ANYTHING!

For the scale stress, put the scale away. Really. Focus on eating, drinking, and moving according to plan and forget about the scale for a while.

If you are feeling lightheaded, stuffed, and uncomfortable after eating, that means you are eating too much in one sitting. A hot dog without a bun may not seem like much, but it is way too much for someone at your stage, so soon after surgery, no matter how small the bites or how well chewed they are. Hot dogs are not the best nutritional choice in the first place, but if you need to be eating about half a hot dog MAX at this time.