Some suggestions:

Easy to prepare and very low in fat: any kind of vegetable cream soup. Since you have to avoid anything that causes gas, maybe choose things like Pumpkin soup, Zucchini soup, Tomato-soup.
Recipe for any kind of vegetable soup: roast an onion (use 1/2 teaspoon of oil), add the vegetable of choice in small pieces, add enough water to cover it up, add salt and pepper. When the vegetables are soft boiled, put it in the blender to get a creamy soup.

I regularly eat an egg and a little bread for lunch, I guess that could be ok for you too?

Easy dinner: Roast lean turkey/chicken or fish in very little fat in a pan, add vegetables (Zucchini, carrots, spinach, bell pepper...) and let them get soft. Cook a little Quinoa or Bulgur and add it to the vegetables.

I guess it's easier to for example eat 3 meals that are higher in calories and 2-3 meals that are very low in calories.
So a typical day would be :
Small Oatmeal for breakfast
Snack: 1 Fruit or dried fruit (I like dried plums) and 1 or 2 nuts
Small lunch (Egg/ Makerels in tomatosauce/ vegetable soup/ cottage cheese and bell pepper/leftover from dinner)
Snack: 1 Fruit or dried fruit and 1 or 2 nuts
Dinner (recipe from above)
Snack: plain yoghurt (or soy yoghurt - I'm not sure if you have to avoid milk in general?) with some berries from the freezer or a little honey

1500 calories isn't much for 6 meals a day, so you have to be careful to eat very small portions for the main meals. Maybe you could get away with only 5 meals, which makes it a bit easier?
It will be much easier if you stock some good choices for snacks.

I hope you get well soon