I am 14 months post op and hit between 900 and 1200 cal a day.
From the beginning post op, up until 6 months, I was hitting only 600 calories a day. I hit a few weeks at 6 months where I stopped losing weight. I went for a visit with my nutritionist at that time, and she said at the 6 month mark, I needed at least 800 calories. Sure enough, when I started hitting 800, the weight started dropping off again. Prior to month 6, even with only 600 cal a day, I had already lost around 70 pounds.
My nutritionist really had me focus on getting in my protein, lower carbs, fluids and vitamins those first months. Calories were never really mentioned prior to that 6 month re-visit with her.
Definitely, with me, I have found it very difficult to reach the calorie limits that other people seem to be able to reach. Even now, at 14 months out, I have to eat about 3 meals a day, which exist of 3 oz tops of protein and a few bites of veggies. Totally fills me up. Then I am able to get in a few "snacks" a day which consist of things like part of an orange, raw red pepper slices or 2 oz rolled up turkey sandwich meat. Sometimes this "menu" doesn't get me above 800 calories, so I will have to throw in an Atkins low carb bar just to boost calories.
Sometimes I think that I am the only one this far out from surgery that struggles to get ìn a 1000 cal day. I even joked with my surgeon and said he must have made my stomach super small. He said that wasn't the case.
I wouldn't worry too much at all if you aren't hitting 1000 cal a day as early post op as you are. You mentioned you aren't always hungry, so that is good. Eat when you are hungry, hit your protein and carb goals, liquids and vitamins. The calories will come.