"I try and snack as much as possible. Eating doesn't make me sick, it's just I often have no appetite."
For the first week or so on a trail, this is about how I feel, too. At day 4 or 5 I am getting my apetite back, but still, not eating as much as I should eat. By day 7 or 8, I am back to eating according to a trail schedule: Big breakfast, hike all day(snacks) and a big supper, often after dark.
Do not worry. You will get enough, provided you bring enough. Your body needs some time to adjust to a working schedule. Some calories all day are important. But, a few lost pounds over a week are really no big deal. Do what makes you COMFORTABLE.
At the end of the first week, you will eat what you didn't eat the first week. Seemingly, you cannot eat enough. By the third week you should start eating less again with your apetite guiding your eating.
Think about the next day, though. Climbing/hiking requires a LOT of calories. If you are doing a lot of hills, force a few extra high calorie foods down at supper. If you will be traveling across flats, maybe you won't need to.