I always have eaten slow my whole life......I still am always the last one eating even at the age of 61.
My favorite foods when I go out are soup & salad....just a cup of soup not the whole bowl......& I figure it gives me reasonable nutrition but isn't that costly in the weight that will be gained. I have to admit now, that there are times when I have thoroughly enjoyed going out with friends & ordering a huge steak & totally enjoyed every bite of it....usually always take home a doggie bag when I eat anything other than soup & salad because I get full so fast that while everyone else is eating their whole dinner, I maybe eat 1/4 & take the rest home....usually the left overs are good for another 4 meals.....so it's ok......justify a lot that way.
But feeling like you are under the scrutiny of your father while being out to eat.....don't think that would be pleasant.....
Let us know how it goes